Columns

Columns is a puzzle game that originated in the arcades and later ported to may consoles. The game borrowed heavily from Tetris, but was not a complete clone.

Gameplay
You controlled columns of multi-colored gems/jewels that slowly descended from the top of the screen. These columns could not be rotated, but the order of the jewels in the columns could be switched around. Like in Tetris, once it is placed, it’s permanent, and you can no longer move that column. When 3 colors are lined up, all three disappear. Unlike Tetris, however, gravity matters. Any gem that is destroyed leaves an open space, which is then covered when the other gems above the hole fall into it. This can lead to several different "combo" gems.

A number of future games, such as Lumines or Bejeweled, feature similar yet heavily altered game mechanics.