Checktris is a complete Tetris clone written in C#. Instead of displaying blocks against a plain background, Checktris displays the tetriminos as groups of checked checkboxes within a field of unchecked checkboxes.
The implementation features bidirectional rotation, both sonic and soft drops, piece preview, Delayed Auto Shift, and Lock Delay. Scoring is identical to the Nintendo scoring system, except that the level is capped at 10 and that drop height points are awarded for hard drops rather than continuously-held soft drops.
The rotation system is modeled on that of the DOS Tetris clone Blocks from Hell, which is to say that it is exactly the Game Boy rotation system with the horizontal I block one tile higher. As in BFH, neither wall kicks nor floor kicks are implemented.
A representative sample of the project's code files is linked directly below. You can play the game by downloading the binary executable included in the zip distribution. The executable as-built requires the .NET Framework 4.