Welltris
(1989 Spectrum Holobyte)


Welltris, which is the first Tetris sequel, was designed by Alexey 
Pajitnov (the creator of Tetris) with Andrei Sgenov.  It was billed 
as "Tetris in three dimensions". 

In this "sequel" of sorts to the classic Tetris, you must deal with 
tiles in 3D, coming in from all 4 sides of a well (hence the name). 
The game certainly retains the addictiveness of the original, while 
making the concept even more difficult -- now you must contend with 
filling 5 surfaces instead of one (the 4 walls, plus the well bottom).