1989 · Puzzle · PC/DOS
Welltris (1989) is an official entry in the Tetris series, designed by Alexey Pajitnov and Andrei Snegov, in which flat pieces drop down the four walls of a well seen from above.
Pieces slide down the walls and, on reaching the 8×8 floor, keep sliding until they hit an edge or another piece. Full horizontal or vertical lines clear. A piece left partly on a wall freezes that wall for a while, and the game ends when all four are frozen.
Pajitnov and Snegov designed it, and Spectrum HoloByte in North America and Infogrames in Europe published it. The MS-DOS version came first in 1989, followed by Mac, Amiga, Atari ST, Commodore 64, ZX Spectrum, arcade and PC-98 versions.