This is a cross post from here: http://guilelessmonk.tumblr.com/
Controls are often taken for granted in a game and yet they are they are the single biggest influence on level design. There are the more obvious examples of this, like if you have a jump button then include the need to jump in your levels but it goes much deeper than asking your player to utilize the mechanics you have put in place. The best showcasing of this is that all the differences between the 2D Mario and Sonic games can be traced back to a single decision about the controls, Sonic has momentum and Mario doesn’t.
Okay, so Mario has a little bit of momentum, but it is barely noticeable whereas Sonic is based around it. In Mario you can stop on a dime and when you move there is no hesitation, this results in Mario feeling more responsive and allowing them to include more intricate and precise vertical platforming in the game. You are routinely asked to jump onto Mario sized platforms from the get go, but in Sonic the smallest platforms you are asked to stand still on are at least twice the width of Sonic, the only things Sonic sized you are asked to land on are boxes or enemies and those can be hit on the move not stop on. The platforming Mario does would drive Sonic crazy because when Sonic tries to jump from a stand still he barely moves at all.
Sonic levels are are designed around momentum. There are slopes to help him build it momentum, slopes to take it away, Sonic isn’t asked to chase around his power ups like Mario after he hit’s his boxes (because that would ruin the “Go Go GO!” flow of the game), Sonic includes obstacles that require a certain amount of momentum to pass through (loops), pretty much everything in the level design plays with momentum.
One of the big problems with Sonic’s focus on horizontal momentum is that it doesn’t naturally use vertical space well on account of the fact that you can’t do precise platforming means that you can’t do the Mario style use of vertical space for exploration. Sonic’s use of vertical space along any given path through a level consists of the use of slopes, Sonic sized obstacles and enemies at varying height. Sonic brilliantly realizes what it can do with the vacuum of vertical space that is left over though and that is branching paths.
Mario levels can’t really use a branching path system (at least to the extreme Sonic uses it) because of the slower progression through the levels and the constant use of vertical space in each level. In addition, the lack of slopes in the game means unless you have a lot of jumping to traverse between each one of the levels (they could’ve also used the Sonic bumpers to do this but they would’ve had to use them even more the Sonic on account of them being the only easy way between paths). Having as many paths as a Sonic level in a Mario level would require several paths to be available on any given screen due to the stop and go nature of the level design. Because Sonic is moving through the terrain so quickly and level design allows for this ‘Go Go GO!’ style of gameplay they can easily support numerous branching paths without making each level feel devoid of purpose.
Controls can make certain actions easy or challenging and realizing what your controls allow the player to reasonably do shows you how to create levels to reinforce what the controls naturally make the player want to do.