The intro level is designed to help the player get adjusted to the mechanics in the game, as well as the core gameplay loop.
Level Two presents the player with an obstacle they must pass. To do so they must travel along a winding path through a relatively small area, without any form of back tracking.
I designed level three to give the player a sense of urgency. They are presented with multiple branching pathways, that all interlock with each other. Giving the level a lot of replayability.
The final level is focused around a boss encounter on a huge bridge. The level starts out in a confined room, which then opens out onto the bridge. This makes it feel more epic in scale.