Zylatov Sisters gives you (and a friend via hot-seat co-op) 13 types of weapons to take on your choice from among 19 challenging, arcade-style levels.
Click to start (no coin necessary!). By default the Left player uses WASD to move and Tab to shoot, and the Right player uses IJKL to move and Enter to shoot. Controls can be customized from the main menu.
Created as a student project at Georgia Tech, as part of the VGDev student organization.
Update: Asya's (right player's) default keys switched from arrow keys to I,J,K,L (similar to WASD in layout) for less cramped controls. As before, they can be remapped to whatever you'd like by using the options at the top of the main menu.