Stupid Zombies is a puzzle shooter rather than an action one: you get a small number of bullets, the zombies are behind cover, and the bullets ricochet off walls — so the solution to each level is a bank shot, not a straight one.
It's a geometry problem with zombies attached, and the good levels are the ones where a single well-angled shot clears four of them.
Bullets bounce off walls at equal angles, so a shot fired away from a zombie can still reach it. Planning that geometry is the whole game.
Yes — that's what makes it a puzzle. Each level gives you exactly enough bullets for the intended solution.
Yes — drag to aim, release to shoot. Nothing to install.