Tetris Zero

Tetris Zero is an unofficial ROM hack of Nintendo’s 1989 NES version of Tetris, created by the hacker known as Infidelity and released in 2012. Its principal purpose is to add a complete simultaneous two-player mode to a game originally sold without multiplayer support. The hack retains the familiar audiovisual presentation and basic gameplay of Nintendo’s original, making the new mode appear remarkably close to an official feature.

The original NES cartridge already contained fragments of an unfinished two-player mode hidden within its code. Although this prototype could be activated through memory modification, it suffered from missing graphics, incorrect colours, misplaced information, unstable music and crashes at the end of a match. Tetris Zero completes and substantially expands this abandoned functionality by introducing dedicated two-player screens, separate controls and correctly displayed statistics for both participants.

During a two-player game, each participant arranges falling tetrominoes in an individual playfield displayed on the same screen. Complete horizontal lines disappear, while allowing the blocks to reach the top eliminates the affected player. Each player receives an independently generated sequence of tetrominoes and has a separate preview window showing the next piece.

Both the endless A-Type game and the goal-based B-Type mode were adapted for two players. The original B-Type requires the player to clear 25 lines, but Tetris Zero allows the target to be set anywhere between one and 80 lines. The second player can also enter a name in the high-score table and independently use the hidden option for beginning ten levels above the selected starting level.

Adding the new code required converting the cartridge from Nintendo’s MMC1 memory controller to MMC3, expanding the program by two memory banks and creating a custom bank-switching system. These extensive modifications make Tetris Zero more than a simple graphical alteration: it effectively completes one of the most conspicuous missing features of the original NES release. While it remains an unofficial modification rather than a separate commercial game, its polished integration and competitive local play make it one of the most notable multiplayer hacks of a classic NES title.