Chess Tactics is a set of chess puzzles taken from real games. Every puzzle comes from the Lichess puzzle database, which is released under CC0, a public-domain dedication. The board is turned so your side is at the bottom. Your opponent has just moved; that move is shown on yellow squares, and a king in check glows red. Find the move that wins.
Tap a piece and then a square, or drag it. Dots mark legal moves and rings mark captures. When your move is right, the opponent replies by itself and you carry on until the line is finished. Any checkmate wins at once. A wrong move is shown, taken back and counted as a miss. Solve with no misses and no hint for three stars; one miss or a hint limits you to two.
The sixty campaign puzzles are grouped by their Lichess rating into five tiers, from Pawn (600 to 1000) to Queen (1900 to 2300). There is a daily puzzle, and Practice offers endless puzzles at the rating band you choose, just for training, with no stars and no coins. Undo takes back your last correct move and the reply at no cost. The first hint shows which piece to move, the second shows the square.
Worked example
Your rook stands on d1 with the d-file open. The enemy king is on g8, hemmed in by its own pawns on f7, g7 and h7, and no enemy piece can reach the back rank. Rook to d8 gives check along the eighth rank, the king has no square to go to, and nothing can block or capture. That is checkmate.
Strategy tips
Checks, captures, threats. Look at these forcing moves first; most puzzles start with one.
Ask what just moved. The opponent's last move often left a piece loose or a square unguarded.
Look for two targets. Forks, pins and skewers attack two things at once, and the solution is often exactly that.