Nice and tricky. (I think.)
In fact I tried to be too tricky and spent a very long time fixing an ambiguity. It was worth it though.
LITS - Nikoli. Exactly one tetromino per region, no 2x2s, they’re connected, adjacent tetrominoes are noncongruent.
theoretical and applied randomness by betaveros
Nice and tricky. (I think.)
In fact I tried to be too tricky and spent a very long time fixing an ambiguity. It was worth it though.
LITS - Nikoli. Exactly one tetromino per region, no 2x2s, they’re connected, adjacent tetrominoes are noncongruent.