Sega Master System / Mark III / Game Gear
Spacegun is one of the rare game that relie on proper 0x000-0x400 memory banking to be correctly emulated. Usually emulator swap the full 0x0000 0x4000 memory region for optimisation purpose. With this implementation of ROM banking, Spacegun will not work. It needs 0x000-0x400 memory region to be untoutched. This game also need light phaser emulation to be playable.