Pulse Bastion

Repel four incoming attackers by forging and aiming a finite shell stock. Tap a bottom pad to aim that column; aiming and choosing shell size are free. Fire spends one shell of the chosen size and one beat. Fuse spends a beat to replace two chosen equal shells with one doubled shell. Attackers advance after every shot, fusion or Wait; reaching the bottom breaches the bastion. The current attacker needs the displayed damage, and the next wave arrives after a kill. All thirty-six points of ammunition are needed: missed shots or overkill leave too little for the remaining armor. Forge the small shells without letting an attacker reach the wall. Keyboard: Tab and Enter/Space operate buttons; R restarts.