cross-tetris: a shared-queue four-well Tetris

cross-tetris is a new game: four standard Tetris wells arranged in a cross, sharing a single piece stream. You — or a greedy rule-based AI — pick which well each piece falls into, the wells play out as ordinary real-time Tetris, and the game ends when any well tops out. The engine is Rust compiled to WASM with a React UI, and it is playable live.