number button - tap to purchase a new fighter, which spawns at the home.
clear button - screen clear (30-second cooldown, will not grant points or cash if used).
strength button - upgrade the damage dealt by every fighter.
red X button - double tap this and your high score will be erased.
tap anywhere but the buttons - this makes the furthest fighter from the touch position go there. Use this to redirect fighters to monsters that are getting a bit too close for comfort or to giant monsters.