You can play an updated version of this game on Steam in the Epic Battle Fantasy Collection. There's new playable characters!
Mouse/Arrow Keys: Movement
Z/Click: Main Weapon: Fast but weak.
X/Double-Click: Sub Weapon: Powerful but charges slowly.
C/Space: Bomb: Clears the screen.
Shift: Focus: Slows down your movement and shows hitbox.
P/Esc: Pause
If the game runs slowly, turn off the graphics stuff in the options.
Also, if you experience any problems with the keys sticking, just use mouse controls instead.