Read the original Co-Op Classics article
One of the oldest co-op titles in the entire database, Space Invaders II hit the arcades in the Golden Age, back in 1980. The game was unusual in many ways, not the least of which was the fact that it was only released as a cocktail cabinet, where players could sit down across from each other. Putting the players in control of tanks at opposite ends of the screen was odd, too. The cooperative elements of the game were fairly light, and friendly fire was a huge obstacle to any sort of teamwork. Still, it was likely the first simultaneous two player co-op shoot-em-up, and that alone makes it a worthy Co-Op Classic.