Games
Move the Tower of Hanoi, jump a knight to every square, and place eight queens. Slide the 15 Puzzle back into order, put your own photo back together, or fill a silhouette with the seven tangram pieces. Then take on the computer at tic-tac-toe, or a friend at five in a row.
Play the classic 15 sliding puzzle in your browser on 3×3, 4×4, or 5×5 wooden tiles. Shuffle, slide whole rows at once, try Sam Loyd's impossible 14-15, or watch Solve finish it.
Turn any photo into a sliding tile puzzle in your browser. Open your own picture or pick an example, choose 3×3, 4×4, 5×5, or 6×6 tiles, and slide them until the photo is whole again, or watch Solve do it.
Play the old Chinese tangram puzzle in your browser. Drag, turn, and flip the seven tans to fill a cat, a swan, a runner, a sailboat, or the square, without overlaps. Ask for a hint, or watch it solve.
Play tic-tac-toe against the computer in your browser. Pick who starts and how well it plays, from Easy to Unbeatable, ask for a hint, or watch it play itself.
Play five in a row, also known as Gomoku, in your browser: with a friend on the same screen, or against the computer from Easy to Hard. Get five stones in an unbroken line to win. Or watch the computer play itself.
Play Connect Four in your browser: drop red and yellow discs and get four in a row to win. Play a friend on the same screen, or the computer from Easy to Hard. Or watch the computer play itself.
Play chess in your browser with all the rules: castling, en passant, promotion, check and checkmate. Play the computer from Easy to Expert, a friend on the same screen, or watch the computer play itself.
Play checkers in your browser: English checkers on 8×8 or International draughts on 10×10, with compulsory captures, multi-jumps and kings. Play the computer from Easy to Hard, a friend, or watch the computer play itself.
Play Reversi, also known as Othello, in your browser. Place discs to flip your opponent's, see every legal move, and play the computer from Easy to Hard, a friend, or watch the computer play itself.
Play a free tower defence game in your browser. Build guns, cannons, frost and sniper towers along the path, upgrade them, earn money for every enemy and survive 20 waves on three maps.
Jump a chess knight to every square of the board exactly once. Play it yourself with Warnsdorff hints, or watch Solve finish an open or closed tour. Save the path as a PNG.
Place eight queens on a chessboard so that none attacks another. Try it yourself, watch the backtracking search find a solution step by step, and go through all 92 solutions.
Move a tower of disks across three pegs in your browser. One disk at a time, never a larger disk on a smaller one. The shortest solution is 2ⁿ − 1 moves.