Every contest is one hard problem with a search space far too big to try everything. Sign in, send your best answers, and climb the leaderboard. Entry is always free.
The rest of the original contests will reopen one by one, with their old records on the board.
Clear 25 boards of coloured tiles for the highest possible score.
Read its story → ReturningColour the largest grid you can, with up to 21 colours, so no rectangle has four corners alike.
Read its story → ReturningA prime-number search that ended in a dead heat at the top.
Read its story →Brand-new puzzles are in the works for the relaunch. Got an idea for one? Pitch it in #contest-ideas on the ISS Discord.
