NullpoMino is a cross-platform, open-source Tetris fan game notable for variety of gameplay modes and customizability. It is a Tetris clone written in Java providing three versions: One using Slick, another using sdljava, the last using Swing. It was created by NullNoname. It simulates numerous games, including the TGM series, and contains a utility for creating (and editing) your own custom rotation systems as well. NullpoMino is one of the few Tetris games, official or not, with a truly cross-platform online vs. mode, the others being TetriNET, Blockbox, Tetris Friends, and MultriNet. Blockles also would have been on this list before its demise due to copyright infringement (TTC has copyrighted and trademarked the tetrimino shapes).