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 games using the scoring system of Tetris Worlds Cascade, which rewards more for higher cascades. Quadra uses left-handed Nintendo Rotation System. Line clear delay functions like ARE in the TGM series: 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, top players have been seen to build at peak speeds upwards of 260 TPM, although for a short duration. The game displays "blocks per minute" of even higher, but these measurements aren't in real time. 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.