SEGA: ‘3D Sonic The Hedgehog 2 Included in the SEGA 3D Classics!’

NintendObserverThis interview is extremely long but also extremely interesting. 


☆ NintendObs Weekly – Monday, October 5, 2015 – Sunday, October 11, 2015.

3D Sonic The Hedgehog 2



Tuesday Oct 06, 2015


3D Sonic the Hedgehog 2 comes out on the Nintendo eShop for the 3DS this Thursday!

This is a translation of an edited version of the article located here:


3D Sonic The Hedgehog 2


We are back with the final game in the second batch of the SEGA 3D Classics series, and the finale for the SEGA 3D Remaster Project. Sonic The Hedgehog 2 was originally created by none other than Yuji Naka for the SEGA Mega Drive back in 1992. Major enhancements such as the helical loops brought both new graphics and an edge to the gameplay, resulting in a huge hit.   Aside from the new stereoscopic 3D, 3D Sonic The Hedgehog 2 packs in Ring Keeper Mode and Stage Select, allowing players to take a more relaxed and enjoying approach the original game. We once again have brought the last and final (?!) special interview with SEGA Games Producer, Yosuke Okunari, and M2 President, Naoki Horii, to speak about the game and close out the series for us.


3D Sonic The Hedgehog 2


Is Overwhelming Manpower Enough? Not Only Are There A Ton Of Stages, But They’re Huge!


It seems like the base porting was a hassle in itself, but what would you say was the most difficult aspect with 3D Sonic The Hedgehog 2? Was this an overall difficult port?

Yosuke Okunari (below YO): As I mentioned in the previous interviews, Streets of Rage 2, Gunstar Heroes, and Sonic 2 were all Mega Drive titles that we wanted to include for Batch 1, but we held off on them because M2 considered them to be technically challenging at the time.


3D Sonic The Hedgehog 2

Commemorating the 16th title of SEGA 3D Classics project is Sonic The Hedgehog 2.


Out of the three titles, Sonic 2 looked as if it would have the most technical issues during development, so we’ve decided to have it as the bookend of the series. If you just casually think about it, you might make the mistake that converting Sonic 2 would a simple task, considering Sonic The Hedgehog has already been worked on. However, there were several new hurdles we had to overcome for Sonic 2.

First off, there is a monumental increase in volume. There’s not much of a difference based on the number of stages, but there are nearly double the amount in terms of zone variety. Sonic 1 consisted of six zones, with three acts per zone, totaling to about nineteen levels plus special stages. Sonic 2 consists of eleven zones, with two acts up to Zone 7 and only Zone 8 having three acts. There are also Sky Chase, Wing Fortress, and Death Egg, which all totals up to twenty stages. On top of all of that, we needed to turn the special stage into 3D, so there were lots of hurdles to overcome.


So considering the amount that needed to be addressed, you guys were in a tough spot.

YO: Well, it’s not like we actually measured them out, but I’m sure the lengths of each stage in Sonic 2 are much longer than those of Sonic 1, so that adds more to our workload. However, if volume was the only issue, we could’ve solved things as long as we had time, like Gunstar Heroes. In this case though, we had two more issues.

The Special Stages… This is where Sonic runs through this half-pipe tube. As much we wanted to make it happen, we were skeptical whether we can turn the graphics for this into stereoscopic 3D.


Sounds like the most easy to envision, yet complicated issue.

YO: Lastly, the Versus Mode. Not many may remember, this game used to have a Versus Mode, where the screen gets split into two with a top half and bottom half. This system is what we could call a display of Naka-san’s true prowess, as it was elaborately designed and utilized interlacing. We were unsure how to replicate this on the Nintendo 3DS. Plus, the 3DS has a liquid crystal display, which doesn’t use interlacing at all.

Around four years ago when these series were originally established, we had agreed that overcoming these hurdles was “impossible,” and thus only converted Sonic 1. However, after three years of accumulated techniques, M2 was able to take on the challenges of converting Sonic 2.


Regarding the first issue, so you’re saying that despite the larger volume, the past strategies would’ve sufficed if it were for the normal stages only.

Naoki Horii (NH below): Yes, to a certain extent. However, the maps are bigger in all four directions compared to Sonic 1, so the resources needing work are an order of magnitude larger.

YO: Not only the map sizes, but the stage gimmicks had some enhancements in theSonic 2 as well. For example, while Sonic 1 incorporated the loop-the-loops where Sonic runs up and flips 360 degrees, Sonic 2 includes spiral paths and other elaborate actions. Turning those into 3D is another hurdle to jump.


3D Sonic The Hedgehog 2


3D Sonic The Hedgehog 2


The majority of Sonic 1 was a one-way progression, but Sonic 2 had players going all over the place. Was that another feature that made it difficult to convert? Considering the conversion for Gunstar Heroes took roughly one and a half years, would you say the same time would be needed for this title?

NH: Before we even got to Batch 2’s Mega Drive games, Okunari-san had stated that he wanted to see these titles in the line-up if it ever happened, so they’ve been on our radar for a while. However, we didn’t officially start the development until we finalized the plan.

YO: They needed to research in order to overcome the technical hurdles of Sonic 2.


So the development process kicked off once your conversion techniques seemed sufficient enough to fix the second and third issues? However, the sheer volume of it all was still a challenge.

YO: With Streets of Rage 2, we weren’t sure if we could render it at 60 frames a second, and if we could apply stereoscopic 3D to scenes that had an angled view. However, the work on Gunstar Heroes and Sonic 2 was predicted upon the work on Streets of Rage 2. A spring board if you will. So whatever issues we had with Streets of Rage 2 weren’t anything major for Sonic 2. Therefore, it was assumed that we could achieve at least 60 FPS for co-op play and find ways to convert all the visual tricks into proper 3D.

With Gunstar Heroes, with time we managed to solve all of the issues that arose in Streets of Rage 2 one way or another. The scroll speed for Gunstar Heroes isn’t too fast, and the maps are pretty standard sizes. Although we needed to implement the ins-and-outs of each bosses, we were able to get through all of it thanks to M2.

With Sonic 2, however, the map sizes are huge compared to the two, and consisted of many parts where we questioned the 3D stereoscopic compatibility, so the difficulty was on another level. The development scale for Sonic 2 was by far the largest in the series.


In other words, you’re saying the man-hour cost was monumental.

YO: Exactly.

NH: We had assumed that as a rough estimate, we would only need three people; a programmer converting the entire game, a programmer dealing with the special stages, and another one developing the Versus Mode. As a result, our budget shot up as well.


Up until now, was one programmer in charge developing one title?

NH: There’d be one main guy, sometimes with a few assistants, but never an instance where everyone puts in equal amount of work into a title. For Sonic 2’s case, we completely separated the production process of the main game and special stage.


So everyone specialized at what they did.

NH: Indeed.


3D Sonic The Hedgehog 2


The Special Stage: Pre-rendered Image Copied With The Naked Eye!?


3D Sonic The Hedgehog 2

Okunari-san’s overseas version teaser poster. We had them take the same pose as in the poster.


I understand that the normal stages were a challenge in terms of volume, but I assume the special stages were a challenge development wise.

YO: The deciding factor for starting this project depended on whether or not it was even possible to convert these special stages. We were still in the development stage of SEGA 3D Fukkoku Archives when we wanted to start this project. We knew it would be hard, but we really wanted to make it work, so we kept bouncing technical ideas off each other to find the most feasible method.

While discussing with M2, one method we both agreed that we didn’t want to employ was the way the mobile version of Sonic 2 does it. That version doesn’t use emulation and is a totally different approach than we use. That version actually uses polygons to render out the Special Stages and it would have turned out to be a completely different product.

If we were talking about an HD version and making a totally different game, then it would’ve been acceptable, but this project was anchored around this “Remastering” concept. It needed to be authentic. We wanted it so if we turn off the 3D stereoscopic switch, it would look exactly the same as seen on a Mega Drive screen. We could have taken the way the mobile version of Sonic 2 does it and converted that, but we requested M2 to find another way.


And despite that, you had prospects of success.

NH: To tell you the truth, not really. We simply had two methods, and would’ve been happy if one of them worked out.

First method was similar to what we did for the Fukkoku Archives version of Space Harrier, where we would cut up the bonus stage, stack five to seven layers together, and add depth, and hope it would turn out alright. After giving it a try, it somewhat looked how it should, but was still lacking something. At that point, we contemplated whether we want to continue with this method or not, and ended up going with the second method.


3D Sonic The Hedgehog 2

Applying 3D stereoscopic to this already looks complicated, but here you see a time-consuming method where they take pre-rendered graphics, adjust each segment, and apply Z depth.


And what’s this other, harder method?

NH: Sonic 2’s Special Stages were actually created out of pre-rendered polygons, and then video of that was compressed and halved both vertically and horizontally, then dropped into the game cartridge. We took that pre-rendered video, reverted it back to its original polygon state, remade our own version of it, then went back and assigned depth on a pixel-by-pixel basis. Therefore, we had to analyze and pull out the data needed to create the bonus stage for Sonic 2. Although these are pre-rendered images, SEGA’s development team would fix some of them up to enhance the looks. However, those sections would look unnatural with the polygons we created, so then we had to tweak the polygon render and create a course that matched the original images, and that’s how we got it running without issue on 3DS.

I can say this only because I didn’t work on it, but if the one in charge of it was here right now, I’m sure there’d be many comments like, “I wonder why we even thought of doing that method?” or, “How could you give me such an annoying task!”


Was it the programmer in charge of the special stage who suggested this idea?

NH: No, it was suggested by someone else, who said it would be the best way to make it look clean. The one in charge started on it saying he’s got the time, so he continued to adjust it from beginning to end. Since his seat was right near the entrance of our company, we’d see the same course from Sonic 2 on the display as we got to work. It may have seemed like there was no work being done, but he was going against an enormous amount of data.


Must’ve been really tough for the guy.

NH: As for graphics, we based everything on the Mega Drive while programming in the Z axis. Movements such as collision detection are same as the original game, since the polygon graphics we recreated only functions to attach the 3D information onto the original images.

YO: Therefore, it’s very unlikely for the difficulty level to increase for playing the Special Stage.


So on the program side of things, it’s the same.

YO: Exactly.


So you guys built some polygon images, rendered out those images to create graphics, just to create the same visuals as the original?

NH: Yes, we were able to create a 3D version of the Special Stage by sort of eyeing the original images and creating polygon equivalents.


3D Sonic The Hedgehog 2


3D Sonic The Hedgehog 2


Props to you guys for doing such a thing!

YO: Thanks to our efforts, we were able to bring out the true 3D effect to life, as you can see.


Another Obstacle: Versus Mode = Lost Hope


3D Sonic The Hedgehog 2

This pair comes up with the craziest solutions. This release is another example of their success.


How did you go about implementing the Versus Mode, your other major issue?
YO: Toward the beginning of this project, we weren’t sure if we could even include the Versus Mode. It was such a major hurdle to clear at the time that going with a risk-free method would’ve delayed the development process by six months.

With Gunstar Heroes and Streets of Rage 2 scheduled to release in the summer, we couldn’t allow only Sonic 2 to be released in the winter, so we agreed to drop the Versus Mode.

However, not too long after the project started, M2 told us, “It seems doable, so can we try and include it,” to which I responded, “Of course, as long as you can stay within schedule. We leave this matter to you.”

NH: I knew they wouldn’t say no to efforts enhancing the game.


On the other hand, was it something you really though was technically possible, even when you were told that you didn’t have to go that far?

NH: I knew that it would’ve been possible from a technical standpoint, but I feared I wouldn’t be able to finish it on time. Therefore, knowing that I didn’t have to do it sort of took the pressure off the team. If we absolutely had to make it, it would’ve been a challenge and stressful to complete.

Another reason is that we didn’t want to not include it at this point in the SEGA 3D Remaster Project. Considering Sonic 2 was the last of the project, I really wanted to include all elements of the game.


3D Sonic The Hedgehog 2

Since Versus mode will require double the information, even a non-techie can see how hard it might be to apply 3D stereoscopic. The two screens are blended as they’re displayed.


What was your reaction upon hearing he could solve the issue with technology?

YO: I was told by M2 that the Versus Mode was unique in from a technical point of view. I wasn’t a part of SEGA back when Sonic 2 was released, and I remember how clear the resolution was when I played the game at home. I was in total disbelief that something this amazing could be done on the Mega Drive.

Since that was the case, I was not surprised to hear that replicating the Versus Mode onto the 3DS was going to be complicated. Plus, while it was essential for Streets of Rage 2 and Gunstar Heroes to be multiplayer games, Sonic 2 was mainly a single player game, so I felt it was more acceptable if we couldn’t do the Versus Mode.

NH: I told a few of my ideas to Okunari-san. The Versus Mode is displayed by having two compressed screens for the top and bottom, but we figured it would be easier to display 1P and 2P separately. In the end, we decided to leave the two compressed screens as is, because players won’t be able to strategize without seeing the opponent. In terms of programming for Sonic 2, we struggled to lower the load for two screens.


I can see how that’s an issue. It’s displaying double the usual load, after all.

NH: Indeed.


Were you guys able to solve the issue by simply finding savings elsewhere?


3D Sonic The Hedgehog 2


NH: Hmm. Actually I wonder how they pulled it off myself (laughs).

YO: Some of the zones had been cut out from the Versus Mode most likely to accommodate two player, hence the limited zone selection.

NH: I’d have to agree on that.

YO: Our main concerns then were along the lines of, “Does our Mega Drive emulator, the Giga Drive, have enough capacity to handle it?” or, “Perhaps it’ll end up looking like it’s running at 30 FPS?” It’s crazy how Sonic 2’s two-player mode runs at 60 FPS, considering we thought 60 FPS would be impossible for Streets of Rage 2.

NH: Although they’re two compressed screens, there’s no difference in line counts, since interlacing still requires you to draw the screen once per frame. We redraw 224 lines, which becomes 1 frame of 448 lines, and this doesn’t change for 3DS. For the actual 3DS graphics, all we do is compress the vertical aspect, and blend together the front and back images. We only change up how we render for two player.

YO: Sonic 2 includes some amazing techniques that hadn’t been implemented in earlier Mega Drive titles. Since it’s a later gen Mega Drive title, it didn’t has as much of a wow factor, but thanks to M2 analysis, we were able to shed light on the excellent features that this game has to offer.

NH: We discovered a lot about them while dissecting it…

YO: Even as an emulator, the Giga Drive doesn’t have all the same capabilities and features that the Mega Drive had, so when you have to use parts we usually don’t and speed them up, well, converting a game that uses everything of the Mega Drive is the most difficult.


3D Sonic The Hedgehog 2


3D Sonic The Hedgehog 2

Various gimmicks can be found in Sonic 2. Enhancing the different functions seemed to be a high technical hurdle to overcome.


There’s no room to spare if you use the system’s full functionality.

YO: For example, Sonic 2 uses the Mega Drive’s transparency feature. Oh and how they display water.

NH: I agree. Sonic 2 includes numerous stages where the water level rises up and down and uses some kind of Z-version parallax scrolling where the colors change whenever the raster switches. We didn’t really look into it, but I believe Sonic 2 is able to use 61 different colors for the water level change. The Mega Drive as a whole has 64 colors, and it changes colors with every increase and decrease. You can really see they put a lot of effort into making this, like hiding the noise that occurs during color changes by displaying many sprites. But no one has to worry about this kind thing these days.

YO: Yeah, but you don’t need those sorts of skills anymore, either. It’s a lost art. Since this project focused heavily on replicating the Mega Drive experience, our biggest bottleneck was to match every little details like they were in the original game because we won’t let ourselves do things that the original Mega Drive wouldn’t do. If this was a simple remake, the Special Stage could’ve been reproduced with actual polygons instead of pre-rendering, and we could have probably had a high framerate that would have been more or less like the original.


This is all because the concept of this project is about ‘remastering’, correct?

NH: Back then, there were many who would develop these kinds of technical improvements, but the general focus has shifted. Things change completely based on differences between using a frame buffer or a line buffer. And if I can say it this way, some people just had a knack for it.


So you can say Sonic 2 is a compilation of all these advancements.

YO: We were able to make Sonic 2 happen BECAUSE it was the 16th title in the lineup.


New Ring Keeper Mode – Only Lose Half Your Rings!


Now I’d like to ask about the new additional content added into Sonic 2.

YO: So as you know we always try to include two new additional things that weren’t in the original, but this time one of those is the Stage Select being a normally accessible feature. This is just to lower the hurdle for getting at the stages later in the game for those who have played the game before.


3D Sonic The Hedgehog 2


3D Sonic The Hedgehog 2

Stage Select is right there, ready to go. Players can start from later stages.


And the main focal point is the Ring Keeper Mode. I feel like there were many people who couldn’t clear Sonic 2 back then. The last boss battles against Mecha Sonic and Eggman Robot were so difficult, that even I, as a heavy gamer back then, lost to them countless times. Thus, instead of recreating an unbeatable game, we wanted to offer a more fun, casual game play, which was possible through Ring Keeper mode.

Although Sonic loses all his rings upon receiving damage, the fact that he only needs one ring to survive is what keeps Sonic games from getting too hard. We lowered that hurdle even more by introducing Ring Keeper mode, which cuts down the ring drop down to only half. So for example, if you had 50 rings, normally you’d lose them all, but now you only drop 25 of them.


3D Sonic The Hedgehog 2


3D Sonic The Hedgehog 2

Sonic’s rings get scattered upon receiving damage, but Ring Keeper mode cuts down that effect to half. Essentially, players are safe until they’re down to just one ring.


So they’re safe until they’re down to one ring.

YO: That’s correct. It’ll keep cutting down to half, until players reach one ring and it drops to zero. You tend to pick up more rings as you progress, so the difficulty is much lower. Another important thing to note is that Sonic will have ten rings when the game starts, so going against a boss shouldn’t be too bad even if you have to get hit a couple of times.


You’re right. It was pretty difficult when restarting right before boss battles.

YO: Therefore, I feel like those who couldn’t reach the end of the game should be able to make it all the way by using Ring Keeper mode.


Would you say you can beat Sonic 2 and help on the 3DS?

YO: Impossible! I was never that good anyway. (laughs). That’s not going happen on Normal mode.


Well the point of SEGA 3D Classics is also to let those people who never experienced and beat the game originally to come back and experience it anew.

YO: Indeed. One of our focuses is to have people who never got to beat the game before to beat it this time. The controllers are a bit different, so the gameplay isn’t exactly the same, but people should be able to gradually progress by saving frequently.


Any lasts words to people looking to play 3D Sonic 2?

YO: I’d say Sonic 2 was the most popular game sold worldwide on the Mega Drive, so it’s a chance for people to play the Mega Drive game that had the biggest worldwide impact, on the 3DS. I personally think Sonic 2 is THE Mega Drive game. An “I am Mega Drive, hear me roar!” sort of thing. I’m happy we could end the SEGA 3D Remaster Project with this one, as the 16th title of the project (this is because the Mega Drive focused heavily on “16-BIT”). The three titles we brought back this time are what we believe are most memorable when you look back at the Mega Drive hardware, so we hope that you enjoy what we have to offer.

NH: I agree with him that having Sonic 2 as our 16th title is significant. Sonic 2 has various stage pieces that the stereoscopic 3D enhances visually, so please enjoy.

Also, it would be great if you could even slightly appreciate the staff who worked on the Special Stage as you play this. I’m more than positive there will be no more instances where someone copies a pre-rendering by eye!

YO: You’ll be able to see the stereoscopic 3D trailer on the Nintendo eShop, so please feel free to check it out if you’re interested after watching this interview.


One Can Only Wish… AC Version Virtual Racing Conversion


3D Sonic The Hedgehog 2

Thanks to all staff for working hard. It’d be nice if the arcade version of Virtual Racing can be brought back too though…


With Sonic 2, the SEGA 3D Remaster Project comes to a close. Please give us a closing comment reflecting on the project.

YO: I’m sure many from my generation will consider the 1980’s as the era of video games, with numerous SEGA games released for arcades and Mega Drives. This project was the perfect chance for us to convert the games from that era, one by one putting our full effort behind it, so I’m very thankful for the experience and it will honestly be a happy memory I take forward with me for a long time.

The line-up consisted of the top titles in terms of popularity… I was a bit skeptical ifThunder Blade really belonged in the top 16, but I’m happy that we got to re-release all of those titles in the 2010s, and I hope they go on to be one of the most beloved series on the 3DS.

NH: I’ve been involved on projects where we bring back really old games for people to play again for quite some time, but these classics for the 3DS have been the easiest to work on because you really get to wow the players with the 3D on these. I usually have a difficult time coming up with ideas so people would want to replay these old games, but the stereoscopic 3D aspect of 3DS was impactful enough to get the crowd going. I’m deeply moved by the fact that my 3DS has become, you could say, a SEGA Console in its own way. I mean, it’s got Thunder Blade running on it! It’s a SEGA Console!


Is there a title you wish you could have converted?

YO: That would have to be the arcade version of Virtual Racing for me. It hasn’t ever been faithfully ported. There’re four ports to date: Mega Drive, 32X, SEGA Saturn, and Playstation, but none of them stayed true to the original.

The Mega Drive and 32X versions were amazing at the time, but I wish more attention went to Virtual Racing rather than Virtual Fighter. I wasn’t too impressed with Winning Run (racing game developed by Namco at the time), which was released earlier, but Virtual Racing really caught my attention. The 30 FPS framerate gave it a smoother effect compared to other games like Hard Driving and Winning Run.

There was also a Grand Prix mode, where people could play 15 rounds for 200 yen when popularity started to die. I remember having so much fun playing with three other people and figuring out when to replace the worn out tires at the pits. I do feel that I want to re-experience that some day. Many have told me that there’s no reason to bring it back when there’s so many amazing racing games out there, but I’ve got a lot of great memories associated with that game, so I’d love to bring it back if I had the chance.

NH: I got to say, I agree. I’d say Virtual Racing since I like to work on those primitive era games.


Despite this maybe being the end of the SEGA 3D Remaster Project, I really hope you can make those happen.

YO: Seriously! But I wonder how many of these “final episode” interviews we’ve had regarding this project. Back during Batch 1’s 3D Streets of Rage episode, I was the one who suggested to put “Farewell!” as the title! I thought that was going to be be the end of the interviews.

NH: I was very surprised that time when I heard we’re continuing this project.

YO: The title we really thought was the end of the series is 3D Thunder Blade, and these interview were supposed to end there as well. But then, we decided to release a packaged version of it, so we embarrassingly came back for bonus interview. That’s when we announced it to be our last, once again, yet continued the series until now.

I’ve been porting older games with M2 for ten years now. The reason we were able to bring such quality classics back is M2’s continued loyalty to SEGA. What started only as a standard conversion, has lead us to go above and beyond, such as adding “HAYA OH” as 3D Space Harrier’s final boss or adding extra modes. This is all thanks to our loyal customers and their constant support as well. I feel blessed to have such amazing customers.


Thank you very much.


3D Sonic The Hedgehog 2


3D Sonic The Hedgehog 2

Okunari-san’s unopened Sonic The Hedgehog 2 package. Why the overseas version…? Regardless, oh, the nostalgia!


— sara at SEGA
Source: SEGA Blog.



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