Dotliner
Two players take turns drawing one line between two neighbouring dots. Close the fourth side of a small square and it is yours — and you go again. That single clause is the whole game, and the whole trouble.
The grid fills quietly for a while. Then it tightens into chains, and the player forced to open one hands the other everything in it. Which is why the real skill is not in taking boxes but in choosing when to give some away — the sacrifice that leaves your opponent with no safe move at all. A game that looks like something for a wet afternoon at school turns out to have a sharp, countable logic underneath.
- A real opponent. Several difficulty levels, from a casual beginner to one that understands chain parity and the double-cross.
- Hot seat. Pass the phone across the table and play a human instead.
- Readable board. Claimed boxes take your colour and your initial, finished edges glow, and the running score stays visible to the last square.
- Room to learn. An undo while you are finding your feet, and an optional hint that points at a safe move — or at a clever sacrifice.
- Your choice of length. A few grid sizes, from a quick skirmish to a long chain-building siege, and a tidy end screen that counts up.
com.boxduel.dotlinerHow much of this game is already decided
More of it than anyone expects. Pick a board and almost every number about the game that follows is fixed — not likely, fixed — before either player touches it.
A grid of m × n boxes has exactly 2mn + m + n edges, and a finished game has drawn every one of them. So the game always lasts the same number of moves, whoever plays and however well. The boxes always add up to mn, so the two scores always sum to the same total. Only two things are left for the players to decide: how that total splits, and how many turns it takes to get there.
The whole game, and the only part still open
Not here: no board, no dots, no line to draw, no opponent and nothing played. No chain, no parity rule, no hint about which sacrifice is the good one. This counts what the rules fix. Everything the rules leave open is the game itself.
The opponent does not cheat
Dotliner's computer player reads the same board you do. It is not given a look at moves you have not made, it does not change its mind about a line once drawn, and the difficulty levels differ in how deeply it thinks — not in how much it is allowed to know. A beginner level plays worse on purpose; it does not play fairer on purpose. When the hard level takes half the board off you with one sacrifice, it earned it.
One mailbox
Bugs, a board that scored wrongly, a question about what the app keeps on your phone — all of it to [email protected]. What Dotliner stores, and what never leaves the handset, is set out in full on the Privacy Policy page.