20Bet

20Bet
20Bet is a floor-laying logic puzzle built on a real carpenter's rule. Every room is a bare grid; you cover it completely with 1x2 tatami mats, tapping any two bare cells that share an edge to lay one down. The one constraint that makes it a puzzle: at no inside corner of the room may four different mats ever meet in a cross. Traditional tatami layouts avoid exactly this "shishou" junction, and so must you - if a corner would cross, some mat has to run straight through it instead.

Some mats start already laid, fixing the one true floor plan for that room. Every single layout, across all twenty rooms, is built by a generator and then re-solved from scratch by an independent checker before it ships, so each has exactly one valid finish - no guessing, no ambiguity.

There is no way to lose. Pick a placed mat back up with a tap, step back with Undo, clear the floor with Reset, or press Check any time to see precisely what's left - a bare cell, an overlap, or a corner that still crosses. A hint lays one more correct mat when you're stuck. Rooms grow from a cosy four-by-four up to a full eight-by-eight hall, and fewer mats start laid as you climb, so the reasoning - not luck or a timer - is what gets harder. Coins are earned only by finishing rooms; nothing is ever sold to skip the thinking.