Blood Bros. (set 3)

To start, press Enter at the title screen to enter the main game. You control a character who can move left and right along the bottom of the screen while aiming a crosshair at enemies on a distant plane. The core loop is simple: survive each wave by shooting down soldiers, turrets, and helicopters while ducking behind cover to avoid return fire. You can also throw grenades by pressing the appropriate button, and you can jump to dodge certain attacks. If you're playing alone, you get the full experience; with two players, you both appear on screen simultaneously, sharing the same life pool in some versions. There's no continue system in the original arcade - if you run out of lives, it's game over - so practice your aim and timing to last longer.