Boots into attract mode. Insert a coin (5 or C), then press 1 for 1P Start (2 for two players) to play. Left/Right arrows move, Ctrl or Space fires. Click the screen first so it captures the keyboard. Sound starts muted, so click the Sound button to hear it. Open the debugger to single-step the Z80, read and write its registers and the 64K memory, and set breakpoints and write watchpoints.