Some people may have trouble figuring out the controls so I'll copy-paste them from the game page for your convenience (really wish you could pin comments here):
Controls (keyboard/gamepad):
Main menu and start screen - Z to start, X to cancel.
Movement - arrow keys/d-pad/joystick (WASD if you're a weirdo)
Shoot Bullets - Hold Z/(A)
VAMPIRE LASER MODE - Press C/(X). Keep holding Z. Only usable with full energy bar, shown on the top left corner of the screen below HP.