a weapon (just use the gun model) that explodes normally when it hits a player or vehicle, but when it any surface spawns a projectile perpendicular to the target surface
for instance, if you fire at the ground, it would spawn a projectile that goes straight up
in addition, a player that- if you're holding down A, S or D- dodges backwards or sideways. in essence, they jump low-to-the-ground and move quickly. jumping while holding W or while not holding any button down causes you to jump normally.