Alien Invaders--Plus! is a shooter for the Odyssey^2, and is a single player experience. It was published by Magnavox.
Alien Invaders--Plus! is a commonly available game for the Odyssey^2. It shouldn't be too difficult to find this game for purchase. In good condition, the game is worth about $8.00. Alien Invaders--Plus! was released in 1980.