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Ultimate Tic-tac-toe
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About the game
Ultimate Tic-tac-toe takes the familiar three-in-a-row game and nests it inside itself. The screen holds a large grid of nine small boards, each one a normal game of noughts and crosses. Win a small board by getting three of your marks in a line on it, and the whole board turns into your mark. Win three small boards in a line on the big grid, and you win the game.
The twist is where you are allowed to play. The square you choose inside a small board sends your opponent to the matching small board on the big grid: take the top right square of any board, and the next move has to be made somewhere in the top right board. That turns every move into two decisions at once, a good spot for you and a bad destination for the other player. If you are sent to a board that has already been won or filled, you may play anywhere.
This is a game for two people sharing one keyboard. There is no computer opponent: crosses always move first, and the players simply take turns.
Playing it here
Ultimate Tic-tac-toe is a CHIP-8 program. CHIP-8 is a simple virtual machine from 1977, created for hobby computers like the COSMAC VIP, and people still write new games for it. This one targets SUPER-CHIP, the later extension with a sharper 128 by 64 screen, and was made for Octojam 1, the first edition of a yearly CHIP-8 game jam. It runs here in the Octo emulator, with the speed and colours chosen for it in the archive.
Click Play and the board appears straight away, with a cross waiting in the middle square. The mark under your keys always shows whose turn it is. F2 saves the state of the emulator at any moment and F4 brings it back. A gamepad works too: the D-pad moves the mark and A places it.
Controls
| Key | Action |
|---|---|
| W A S D or arrow keys | move the mark one square: up, left, down, right |
| E or Space | place the mark |
| any key (after a win) | start a new game |
| F2 / F4 | save / load the state |
A few things worth knowing
The cursor knows the rules. After each move the mark jumps to the small board where the next player has to play and will not leave it, so you never have to work out the destination by hand. Placing on a square that is already taken does nothing.
Think one move ahead for your opponent. Before you take a tempting square, look at the board it sends the other player to. Handing them a board where they already have two in a row is the classic way to lose.
Keep a fresh board handy. The game has no screen for a drawn match, so if neither player can make a line on the big grid any more, there is no way out from inside the game. Press F2 on the empty board at the start; F4 then brings it back whenever you want a new game.
Credits and licence
Ultimate Tic-tac-toe was created by the developer who goes by "your name here", who wrote the code and drew the board. It runs here in Octo, the CHIP-8 development tool and emulator by John Earnest (MIT licence). The game is kept in the Chip8 Community Archive, which places everything in it in the public domain under CC0 1.0. The licence text is linked from this page.