ATetrisClone is a blatent copyright infringement of the Tetris game created by Justin Pombrio, written in C++.
It is, however, much more flexible than ordinary Tetris.

The basic controls are the arrow keys to rotate and accelerate a block and the spacebar to drop it to the bottom.

This program is easily modifiable. It uses tab-delimited text files in the Data folder to set various properties.
The piece types, board size, colors, speed, and scoring are all customizable.

To change the pieces, replace pieces.txt with one of the other piece files in Data/More Pieces.
Try fiddling around with the other properties- after some adjustment, you should understand how the parameters work.
And have fun!