Prohibition is a side-scrolling shoot'em up taking place in New York in 1930. The town is overrun by gangsters and you're hired by the police to rid the town of them.
The gameplay is simple: you're facing a row of buildings, a gangster pops up and you have to shoot him before the on-screen timer goes out and he shoots you first. You can hide until the timer restarts but this is limited too. At the end of each stage is a bonus round where you have to shoot gangsters in a room, with no more ability to hide and a faster timer. As you progress through each stage, the game will become faster, and enemies will become harder to find and to hit. Of course, your goal is to reach the end of the game with the highest possible score.