Level Design Analysis: Sonic CD

Original post date: 12/19/11

As many readers already know, Sonic CD was re-released last week (on my birthday, no less) on Xbox Live Arcade. As this was a favorite game from my youth — in fact, I still have the original Sega CD version — and I had 400 points to spare, I downloaded it the day it came out to see how the new release held up. I’d heard that this was supposed to be the definitive version of the game, and so far, I’ve not been disappointed.

I have, however, been enlightened. I haven’t played this game with any serious intent in many years, and since the last time I played, I’ve also started studying game design. During this play through of the game, something very interesting has immediately captured my attention. I always knew that Sonic CD was different from other Sonic games, even when I was a child, but I never really evaluated why that was. I had previously always assessed the differences as simply the fact that there was a new mechanic in play (namely, the time travel). As it turns out, Sonic CD stands out from the rest of the StH series, and indeed from many platformers in general, because of its very unique sense of level design.

Gaming Goals

The plot of this game revolves around time travel. Dr. Robotnik has seized the time stones and systematically manipulated the past in order to create a dystopic future in his own image, and Sonic is charged with setting things right again. This is executed in one of two ways: Gather the time stones, which is comparable to any Chaos Emerald fetch quest, or travel to the past and manually right the wrongs that Dr. Robotnik has committed. Both of these plot points are optional, but with the penalty that the “future” of each stage (aka the third act) is dying and overrun with machinery if this objective is ignored. Additionally, the player gets a slightly different ending sequence upon beating the game.

When I was a child, I played Sonic CD the way I played any other Sonic game; that is, my goal was to get from point A to point B as fast as I could and carrying as many rings as possible. The time travel was interesting, but for the most part, I felt it got in my way, so I actually did my best to avoid it if possible. I did occasionally go to the past and get a good future, but only for an act here or there; it was never something I pursued seriously. I imagine that many other players had the same M.O. with regard to making their way through the levels, as I’ve often heard from many people (both casual players and reviewers alike) that Sonic CD is much shorter than other games in the series.

This is a particularly poignant choice of words. Sonic CD, when played in the conventional StH fashion, is indeed short, but in more than one way. It’s short both in terms of the amount of time it takes to get through it, but it’s also short in terms of course distance. In my review of the StH series as a whole, I mentioned that if I had to describe Sonic levels in one word, it’d be “long.” This is because the primary goal of most of Sonic’s levels boils down to, “Make it past this string of obstacles and reach the end of the track.” Obstacles come in the form of pits, lava, spikes, enemies, etc.

But some of you may be asking, doesn’t Sonic CD follow this formula as well? Well, not exactly. It has many of the same elements, such as the spikes and enemies, but getting from point A to point B isn’t the primary goal of the level design. Sonic CD is fundamentally different from the rest of the series because the levels aren’t designed to be a series of challenges; the levels themselves are the challenges. The obstacles sprinkled throughout the stages are trivial when compared to the greater obstacle of the level itself.

Hiding in Plain Sight

As previously mentioned, when I was a child, I didn’t bother too strongly with the time travel element and just focused on getting through the game. I beat the game many times, but I never actually got the good ending, both because I could never get all of the time stones (I admit that I really suck at this game’s specials stage) and because I’d never made it a point to clean up all of the zones in the past. Even when the game was re-released in Sonic Gems, I never bothered trying to get a good ending. It was because of this lousy track record that I decided I ought to play this game the “right” way at least once. I’d be getting XBLA achievements for it in this case, anyway.

This was the point at which the real challenge of the game began to emerge for me. The stages are short in terms of length because length isn’t the goal; the goal is to get to the past and destroy one animal-capturing machine (aka a holographic projection of Metal Sonic) and one robot-building machine. In this sense, the theme of each stage is a combination of puzzle solving and exploration. The main obstacles of these challenges can be broken down into the following:

  1. Making it to the Past — While this may seem obvious, it’s not as simple as it initially sounds. At the beginning of the game, it’s easy to get to the past; there are lots of Past posts around, as well as plenty of flat stretches, bumpers that can be repeatedly bounced into, and long tunnels to roll around in. However, with each passing level, all of these things become harder to find. It becomes increasingly difficult to find a Past post at all, and then once this is accomplished, it’s even more difficult to find the right place to actually get to the past. In most cases, when you find a sign post, there’s some sort of terrain nearby able to facilitate time travel — or at least, it would seem so. As the game progresses, the level designs become much more deceptive, with paths that would seem ideal for time travel often turning out to be just barely too short. What’s worse is that, if the player starts to time travel but suddenly stops, the sign post is still used up, and the player must seek out a new one. In later levels, this can be asking a lot.
  2. Staying in the Past— Again, this would seem obvious, but it’s much harder than one would think. Just as the appearances of Past posts becomes less frequent in the present, the instances of Future posts (and opportunities to time travel forward) increases at the same rate in the past. It becomes more and more difficult to make one’s way through the past versions of stages without encountering a Future post, and with certain areas of the level requiring a high-speed boost of some sort to progress, it can be perilous to make it through without accidentally returning to the present prematurely.
  3. Navigating the Past — Just as with the other items on this list, this task is not always straight-forward. Sega was very clever in their approach to the different versions of each stage. It’s not simply a matter of swapping out artwork and music; the entire level itself changes, in keeping with the fact that areas change over time. The changes aren’t dramatic (usually…), but it can make getting around more difficult than anticipated; a vital spring may suddenly be missing, for example, or a new wall may have turned up right in the middle of the intended path.

And don’t forget, this still has to be done within the usual time limit of 10 minutes.

To Sega’s credit, they’re not completely unforgiving. While I do think that some stages are pubes-rippingly difficult to navigate in different periods (I used to swear there was one act in Stardust Speedway that could not be finished in the past), the player is at least given a break in the form of rings. Any ring that has been picked up in the present will regenerate in the past, and most likely in the future as well (I’ve not verified this as of yet). The locations of the robot generators and hologram projectors are consistent and usually aren’t too far apart, and in the case of the generators, they can be seen as rubble in the present and future. Best of all, once a baddie is destroyed, it stays destroyed. This is partly because the enemies aren’t the real challenge of the game, and also because some time travel segments require (or are at least easier if) the robots have been cleared from the path in advance.

A Wise Move

The reason this game is able to be so different from the rest of the StH series without feeling uncomfortably out of place is due to the fact that Sega was wise enough to not make time travel required. If the player so decides, they may still opt to breeze through the levels as fast as they can manage, just as I did myself as a child. Clearly, a lot of people did this, which is why many reviews say the game is good, but short and a little too easy.

Some readers might then ask why Sega didn’t then make the levels longer and the enemies harder for those that were interested in a more traditional play through. My answer is that, from a game design perspective, it would have made the game too difficult to complete with its intended goals. Given that the real object of the levels is to get to the past and destroy the two machines, and do so within the 10 minute time limit, a longer level would have made this task too arduous to be fun; it would have essentially changed it to finding two needles in a haystack. Exploration, by definition, requires time. If the arena were to be made bigger, it would become too difficult to explore the stage long enough to find both machines and get out before the time expired.

I suppose an alternative would’ve been to make the time limit longer along with the level, but it’s not an avenue I would take in this case due to the 15 minute rule. This is a game design rule of thumb that suggests a player ought to be able to complete a level or hit a checkpoint approximately every 15 minutes. Although that sounds like plenty of time for a player to complete the time traveling goals for each act, the game’s save system only updated the player’s progress each time they advanced to a new level. For the time that this game came out, that 15 minutes needs to cover all three acts for the average player — which it does, as a typical playthrough that ignores the time travel takes roughly 3-5 minutes per act. Truncating the levels makes the searching more condensed and less frustrating.

This is also why the game’s bosses are relatively easy to beat. In most cases, Sonic CD‘s boss battles are over after three hits; in fact, the boss of Tidal Tempest only requires one. This is another point that I’ve heard the game take criticism for, but when you realize that this game has abnormal goals, it puts those fights into perspective. The challenge focus of this game is in the level design, not in the enemies. Enemies in this game are designed to be pesky more than anything else, and the battles with Eggman revolve more around figuring out his gimmick of the moment (although I will say, some of them were pretty creative). These fights too have respect to the 15 minute rule, as a player that takes the time to go to the past may have already spent 20 minutes (or more, if they lost a life) working on the level. An overly-difficult boss battle would’ve extended the required playtime even further.

That having been said, I do believe that the boss fights could’ve been made at least a little harder without detrimentally affecting the game too much. I believe this because boss fights only occur in act 3 of any level, and these acts are the only ones that do not involve time travel; by the time act 3 hits, you’re stuck with whatever future you’ve made. This means that the player has a full 10 minutes to devote specifically to the battle. Even though I just made a point about the bosses being quick to respect the 15 minute rule, I do think they could’ve been just a tad more challenging without fundamentally changing the design. If Sega had made the bosses require a little more damage — perhaps the traditional six hits instead of three — it might have been a better use of the time. It would have required more effort from the player, which would’ve made the victory more satisfying afterward. I suppose the team might have felt that after all of the time travel and searching, the player may have been too mentally drained for a longer battle, but I don’t feel three extra hits to the boss would have been asking too much.


Overall, I think Sonic CD is an intriguing departure from the norm. It takes players in a new direction while still allowing them to stick to the roots of the StH franchise — something Sega’s struggled with over the years. It’s often said that one must examine history to improve the future; perhaps Sonic CD could become a case study on how to incorporate new ideas into the series without taking them so far astray that Sonic’s essence is lost. A little homework never hurt anyone, and I’m sure Sonic’s fans would really appreciate it.

SONIC THE HEDGEHOG characters © SEGA, SEGA, the SEGA logo and Sonic The Hedgehog are either registered trademarks or trademarks of SEGA Corporation. All rights reserved.


About Leedzie

Leda "Leedzie" Clark is a writer and game designer with a sharp eye for detail and a kooky sense of humor. She's been a nerd as long as she can remember, and always seems to notice the wrong thing first in any given situation.

Posted on April 11, 2013, in Analysis, Feature Articles, Journalism, Level Design, Retro Games, Video Games and tagged , . Bookmark the permalink. Leave a comment.

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