Quadra

Quadra was originally developed and marketed by Ludus Design, but became open source software in August of 2000. Because of this, the game evolved some unique features. Quadra was much different from Tetris from the start. Firstly, unlike many fan games from its time, the name of it didn't end with -tris. It also implemented recursive gravity. An average player can clear nine lines or more. Quadra rewards more for higher line clears, unlike Tetris Holding Company games that rewards more for higher cascades. The rotation system is similar to TGM rotation, but Z, S, and I all rotate leftwards from horizontal-- no wall kicks. A type of ARE exists because of line clears. During which, a player can move and/or rotate once (not needing to hold the button down), and after the animation, the piece will preform those actions. The game also has smooth piece falling like that of The New Tetris. With the presence of fast DAS and double rotation, inbetween line clear animations top players have been seen to process tetrominoes of upwards of 260 TPM. The game displays "blocks per minute" of even higher, but these measurements aren't in realtime. Quadra also features demo recording and playback, multiplayer online, and an online high score table where spectators can download the demos of the top six games.