Aquaventure

Aquaventure is an unreleased Atari 2600 game from 1983 which was later included in various official Atari game compilations. The player controls a diver and must swim to the bottom of a underwater trench while avoiding fish to reach some sunken treasure, then swim back to the top with the loot to the mermaid waiting for them. The player only has so much time per level to do this, as their tank of air steadily depletes. If the player runs out of air, gets hit by a fish, or hits the sides of the trench, then they drown, lose a life, and start the level from the beginning if they still have lives left (if not then it's game over). The main goal, like with most games of this vintage, is to get a high score. Successfully collecting the treasure awards the most points and additional points can be acquired by shooting the fish, however doing so makes the fish move faster. As the levels go on the speed that the fish start at gets faster, and the number of screens the player must swim through to reach the bottom increases.