Take turns placing a stone from your hand on an empty square of the 4 × 4 board. Your stones are blue and face up the board, the opponent's are red and face down.
Fights: each side of your new stone that touches a red stone fights it. Facing spikes break off one for one, and the side with spikes left over wins and takes the other stone. A spike that hits is used up, so 2 against 1 ends 1 against 0. Lose any of these fights and your new stone is taken.
Chains: a stone that changes colour fights on with its own spikes, the pair closest to the new stone first, until no blue and red stones touch with a spike between them.
Winning: when the board is full, each stone you own is one point. Level on points, most spikes left wins (the ▲ number). Level on spikes too, whoever placed first wins.
Stones
Each level adds a spike to every side that has some, up to 5. Opponent stones start at level 0: one spike fewer on every spiked side, so a level 0 Tiny has none.
King Kobe has golden shields: every spike that touches him breaks, and he can never be taken.
Rare stones have their own powers and their own growth (see below). Each belongs to one opponent, who always brings it.
A run
A run is 20 matches, and match 20 is the boss. Lose one and the run is over. The difficulty is picked once per game (New game, below, starts over with the starter stones): Easy (opponents look 2 moves ahead), Normal (as far ahead as they can), Hard (2 moves) or Very hard (as far as they can). The card shows how many levels their stones gain per win.
Before each match you see the opponent's stones and the 8 of yours you take in, at most one king and one queen: the same stones as last match, even in a new run. Fight plays them, Change stones swaps some.
After each match you win, every opponent's deck gains levels, one stone one level at a time. On Easy the Tinies go first, on Normal the Tinies, knights, bishops and rooks. The boss skips the first few upgrades. Lady Lux, whose Experienced Edna cures poison, always comes before Madame Swerve and her Venom Veronica.
After a win you get a new stone: one the opponent played or a pawn or knight turn you do not own yet. It goes into your deck by itself only when it has more spikes than your weakest stone there. Then upgrade one of three stones from your deck by one level (the old one stays, except a queen, who is replaced). When a run ends, keep one stone you gained in it for good.
Controls
Pick a stone (or press its number), then point at a square, or tap it once on a phone: yellow stones you would take, red stones you would lose, faded spikes would break. Slow (or S) plays every move four times slower.