If the game freezes, just click inside it (games can get unresponsive if you click elsewhere on the page).
This is a retro-styled game where you choose a pair of characters, travel the world and kill everyone you meet.
Left / Right Arrow Keys - Move.
Up Arrow key - Jump.
Down Arrow Key - Crouch.
S - Punch.
A - Kick.
D - Switch Character.
S+A - Special.