Arrow keys to move, z to attack. Try not to have a bad time. Attempting to attack can heal you via determination.
EDIT: Game now works in 3.0 I think I'm done working on this. It should be completely playable, you should never accidentally stumble upon this while I'm working and experience an unplayable version, and when you remix it, everything will work and look good. Well, except for the "Bad time" segment, but I wasn't really going to elaborate on that, so it's just hidden code. Anyway, credits and notes below: All coding from me, except for the text engine, which was by Jackbotic All music/sounds from Undertale Sans, Fight button, Gaster Blaster and Game Over sprites from Undertale, the rest were done by me from memory. You can use the source code for whatever you want, and I will probably release the template soon If you do use it, credit me I guess. Edit 12/5/15 The lasers are now Gaster Blasters, and do 1/3 of their original damage.