Blockout
Platform: Atari Lynx
Region: USA
Media: Cartridge
Controller: LYNX Gamepad
Genre: Strategy 
Gametype: Licensed
Release Year: 1990
Developer: Logical Design Works, Inc.
Publisher: Atari
Players: 1
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Blockout is a Tetris clone with an added twist: it's in 3D. You can rotate the blocks in 3D in order to fit them into the pit they are being guided into. Advanced users can play this game with odd three-dimensional pieces, or change the size of the pit, for depth of between 6 and 18 piles, and width and length of between 3 and 7.

Trivia:

Unlike Welltris (which billed itself as Tetris in three dimensions), Blockout was the first true 3D Tetris variant.

http://www.mobygames.com/game/lynx/blockout