Dr. Mario GAMEBOY

Dr. Mario, ported to Game Boy in 1990 following its NES release the same year, casts Mario as a doctor dropping color-coded pill capsules into a bottle full of viruses, clearing them by lining up four or more matching colors in a row — a falling-block puzzle format that predates it, but one Nintendo made distinctly its own through presentation and the specific two-color-halves mechanic of each capsule.

The core rule that separates it from a generic Tetris clone is the split capsule: each piece is two connected color blocks that can be rotated and, once placed, separated permanently if one half clears while the other doesn’t — meaning the board state gets progressively messier and more interesting to read as a stage goes on, not just faster. Clearing all the viruses on a level wins it; letting the bottle fill to the top ends the game.

The Game Boy version’s two-player link-cable mode, where clearing multiple lines at once dumps junk pieces into the opponent’s bottle, predates the same competitive mechanic in Tetris’s own multiplayer modes on the system and made Dr. Mario one of the more popular head-to-head handheld puzzle games of its era.