Siege!

Siege is a fixed-screen action game where the player defends a medieval fortress from enemies attempting to scale its walls. Positioned atop the battlements, the player controls a character who drops boulders onto the climbing attackers to stop them from reaching the top. The player moves horizontally along the top of the wall and must time boulder drops to hit enemies as they ascend. The game increases in difficulty as enemies climb faster and in greater numbers. No scrolling or projectile aiming is involved; success depends on timing and positioning.