This game has a custom rotation system that is based on SRS/ARS (selectable) that allows most of twists to be done, including T-spin triple. It also allows O-spin, I-spin tetris and diagonal slide (if left/right movement fails, it tries downleft/downright).
The above-mentioned rotation systems are the Tetris Best rotation systems (there are 2).
Note: This game works best on Firefox, and turbo mode (shift+green flag). The performance also increases with a faster computer. Also, some users may be unfamiliar with this game because up arrow is hold, while in most games, up arrow is rotate.