17. Bubble Bobble
Fun Fact: Developer Taito lost the source code to the NES version of Bubble Bobble in 1986.
Bubble Bobble enjoys a reputation as one of the best co-op experiences in the entire NES library. Each player controlled a cute Bubble Dragon named Bub or Bob. The goal of the game was to travel through hundreds of stages to rescue Bub and Bob's girlfriends from the monsters.
Bub and Bob could blow bubbles that were used as platforms to rise through the stage or trap enemies. To kill an enemy, players had to pop the bubble once the enemy was trapped within it. Killing an enemy released food into the level that was worth points. Enemies moved faster if they were trapped in a bubble and then escaped, and as the number of enemies on the screen decreased.
There were over a hundred stages in Bubble Bobble, and some of the designs were pretty bizarre. Power-ups throughout the stages would shoot lightning bolts across the screen when picked up, or speed the players' movement, or increase the speed at which they could blow bubbles, or allow players to skip levels. Bubble Bobble was also an early example of a game that had multiple endings.