The level design up on the open surface pretty much only takes you right, along the ground, and with several pools of lava to leap over. There can also be the occasional steep slope now and then, and bumpy terrain throughout the stable areas. Down in the dungeon though, the level becomes nothing short of a large, complicated maze. You'll be heading back and forth through narrow, compressed corridors, positioned to create an intricate path of tunnels that weave up, down, left and right between each other. The more open areas inside usually contain a long pool of lava at the bottom that you'll have to be careful of, when hopping across platforms above it, or riding on a small block that floats along. You'll also have to make your way up steep steps that are cut into the walls, but be very careful of large crushers that drop by chains from the ceiling, in the open vertical passages. All the paths underground are made up of perfectly straight brick surfaces, though the steps in the vertical sections can get fairly small in places. As for multiple routes, there are a number of secret areas hiding power-ups around the maze, but the only real choice of route you get is in Act 3. At the begining, you can choose one of two different entrances into the rest of the maze, and later there is a secret shortcut inside the foreground walls that cuts out a sizeable portion of the act. Everything else is largely based on one, solid path though. A very slow level, but filled to the brim with traps and tricky bits, and there's alot of platform hopping to do too.

Badniks common to this zone are the Buzz Bombers from Green Hill, who lurk above ground only, aswell as Caterkillers, who work their magic all over the place. They're a classic worm bot, with many variations later on in the series, that slowly wriggle around a set area. Hit them on their heads only, or you'll take a hit, and worse, the pieces of their spikey bodies will scatter, causing more problems. In narrow corridors, use your rolling attack to take them out safely, when they're facing your direction. In the dungeons only, Batbrains often hang from ceilings, usually in clusters, and flap around when you get close, sometimes taking you by surprise.

- In some early screenshots of Sonic 1, including beta versions and pre-releases, etc, the Marble Zone looks fairly normal, except that it seems to be infested with mysterious, round UFO objects, or possibly ringed planets in the sky. Needless to say, these did not make the final cut, but one has to wonder just what is up with that? Believe it or not, this mysterious phenomenon also appears at the very beginning of the movie "Wayne's World", which features a brief clip of the game. It seems to be an early version, and the UFO's/planets are right there in it, in the Marble Zone!