Enclosure

Pieces drop to the lowest free cell of a column, like Connect Four, on a 6×7 board.

You win by enclosing opponent pieces: build a closed ring of your own pieces (diagonal links count) around them so they can't reach the board edge.

The bot runs Monte Carlo Tree Search: thousands of random play-outs from the current position, steering the search with UCB1 (exploration constant C). "MCTS + tactics" first checks for immediate wins, blocks, double threats and edge escapes.