I built this simple puzzle generator to play around with wasm a bit.
It's open source if anyone wants to play around with the code https://github.com/lnenad/puzzlip
But I agree that applying different styling to tiles on both hover events and mousedown events would make it feel snappier.
(I've only tried this on desktop. Haven't tried it on mobile)
I also wonder how hard it would be to tile with different shapes. Hexagons or squares and octagons could be really neat.
I wonder if there might be a way of changing the difficulty without changing the number of pieces? Like maybe putting gridlines between the pieces, so that you can't actually see the seamless connection between two correctly-oriented pieces?
Any chance you can load a bunch of stock photos into the various categories? I think there's only ~8 or so in each.