Chew Man Fu

Gameplay is something of a Pengo variant, as the single-screen levels are inhabited by enemies, who can be killed by firing one of the balls at them at speed. When it hits one it will continue moving in the same direction, rebounding off walls if necessary, and pushing you backwards slightly if it comes back to you - but it can be instantaneously brought under control. Blocks can also be moved at a more casual speed, including round corners. Once a block is placed onto its spot, it can be used again as a weapon.