Bubble Bobble

In this game, each player controls one of the two Bubble Dragons, Bub and Bob. The player can move on the platforms and jump to the platforms above and to the side, similar to most platform games. The player can also blow bubbles. These can trap enemies, which are defeated when the bubble bursts with the player's spiky back. Bubbles that have enemies trapped in them can burst at the same time, causing various food items to be flung through the level. Each enemy trapped in a bubble corresponds to a different food. The food is consumed and converted into points (an increasing scale of 1000 points is awarded for each burst enemy associated with another, i.e. one burst enemy corresponds to one food worth 1000 points, two burst enemies correspond to two foods worth 1000 and 2000 points, three burst enemies correspond to three foods worth 1000, 2000 and 4000 points, and so on), earning lives. These bubbles also float for a while before bursting, and can be jumped on to reach otherwise inaccessible areas. Players advance to the next level when all enemies in the current level are defeated. Enemies become "angry" - they turn pink and move faster - when they are the last remaining enemy, when they escape from a bubble after staying there too long, or when they have spent a certain amount of time in the current level. A monster also gets angry when one of the two players collects a skull (the only negative item in the game) and the monster gets hit by the resulting comet that crosses the screen (this rarely happens, though). After another time limit expires, an additional invincible enemy appears for each player, actively chasing them while performing only vertical and horizontal movements. These do not need to be defeated to complete the level, and disappear once a player loses their life. Contact with the enemies and their projectiles (rocks, lasers, fireballs, etc.) will result in death.