This game is a two-player color version of Asteroids. It has two different modes of play: competitive and team. In competitive mode, each player competes for points. Players can shoot each other for bonus points, but they don't lose a ship. In team mode, the two players are attached together by a tether. Each player's ship can move and shoot independently while still being attached.
Space Duel has examples of:
- Asteroids Monster: Here they are cubes and "fuzzyballs".
- Deflector Shields: Players can briefly protect themselves with one.
- Everything Trying to Kill You: Just about every object that appears on the screen will be able to damage you. That is, besides...
- Friendly Fireproof: Players in the competitive mode may gain bonus points from shooting at each other in the competitive mode, but they don't take any actual damage.
- Giant Mook: The large cube and pinwheel enemies that are 2-3 times larger than either the "normal" cubes, or your ship.
- Mercy Invincibility: One occurs for a few seconds after you respawn.
- Mini Mook: By contrast, the smallest cubes and pinwheels that the normal ones split into are this.
- Nintendo Hard: While the first minute or so is enough when there only the "pinwheels" lazily drifting about, the difficulty rapidly ramps up once giant versions of normal enemies and the opponents that can actually shoot back show up, especially since they can appear from any side of the screen.
- Video-Game Lives: Like in most such games, the player has three lives.
- Wrap Around: Present.
- Zerg Rush: Stick around for a minute or two, and the enemies will begin arriving in real numbers.