Dustforce

Dustforce is a 2D side-scrolling platform game starring a team of broomsweeping janitors. Players select one of the four available characters and need to complete more than 50 levels. These are accessed from a central hub that is further opened up through keys. Each door represents a new level. Some of them have a level completion requirement before they can be accessed. After each level the player is rated based on the completion rate (sweeping all dust), finesse (holding on to a combo) and time. Often a key is received for perfect levels. Global leaderboards are supported as well as local multiplayer.