Every board is checked to be solvable before it ships, and the difficulty climbs on a curve rather than a cliff.
Past level 500 the game generates new boards for ever, growing larger and introducing new shapes as you go.
No account, no sign-in, no cloud. Your progress lives on your device and the puzzles work on a train with no signal.
Three free hints a level, more on the harder tiers. They cost points, never lives, and never finish the puzzle for you.
Sand, Mint and Midnight, with an automatic mode that follows your device between light and dark.
A single purchase turns off every ad for good. It restores on a new device, and nothing about the puzzles changes.