Controls
- Joystick: Use the 4-way joystick to direct Monster Fighter around the screen; when the warp zone in the centre of the screen starts flashing white (with the Katakana text Wāpu ワープ in the original Namco version or the English text "WARP" in both Rock-Ola licensed versions), move into it to warp from Space World (which he'll always begin each round in) to Maze World (or, if he is in Maze World, warp back from there to Space World).
- Firing Button: Use this button to make Monster Fighter fire his gun at the enemies, or, if he's in Maze World, lay a time-delay bomb; each time he kills a Berobero in Maze World, his bombs grow stronger, which makes it easier for him to blow himself up (however, if he dies as a result of being blown up by one of his own bombs, their power shall be reset, unless he happened to be down to his last life in which case it costs him the game).
- 1 or 2 Player Buttons: Push these buttons to begin a 1 or 2 player game.
Characters
Monster Fighter
The protagonist of the game; you must use the 4-way joystick to direct him around the Space World, along with the Firing Button to make him fire shots from his gun at the Berobero. If he kills three consecutive Berobero of the same colour a mystery alien shall appear on one edge of the screen and start making his way towards the edge on the opposite side of the screen - and when the warp zone in the centre of the screen starts flashing white, he can move into it to warp to Maze World where he can kill the Berobero by laying time-delay bombs.
Berobero
These tongue-sticking aliens are the primary enemies of the game, and there are twenty of them in each round; they shall change colour from yellow to orange to red as they get closer to the centre of the screen, and when they are in the Space World, they shall attack by firing bullets at Monster Fighter (which he can block with his own shots but aren't worth any points). In both worlds, they also possess the ability to kill Monster Fighter by touching him.
| Yellow | Orange | Red |
|---|---|---|
 |
 |
 |
| 60 points | 90 points | 150 points |
Mystery Aliens
| Alien | Description |
|---|---|
 |
Kaeru (green frogs) shall appear if you kill three consecutive yellow Berobero (when in the Space World) and are worth 500 points. |
 |
Tako (blue octopuses) shall appear if you kill three consecutive orange Berobero when in Space World, and are worth 1000 points. |
 |
And Kani (magenta crabs) shall appear if you kill three consecutive red Berobero when in Space World, and are worth 2000 points. |