Which commercial version of Tetris sold about 35 million copies?

The Game Boy version of Tetris sold about 35 million copies.

Nintendo released this portable adaptation in Japan on June 14, 1989, with North American and European releases following. It was bundled with many Game Boy systems, helping turn both the handheld and Tetris into worldwide successes. The game was developed by Nintendo R&D1 and produced by Gunpei Yokoi.

Its success also grew from its accessibility: the monochrome screen, simple controls, and battery-powered portability made Tetris ideal for short sessions anywhere. It introduced two-player competition through the Game Link Cable, with cleared lines sending penalty rows to an opponent.

A common mix-up is confusing this figure with other releases. Nintendo's NES version was also highly successful, but its reported sales were much lower. Tetris DX, the later Game Boy Color update, is a separate release rather than the version associated with the roughly 35-million figure.