Color Sort

Josie played one of the mobile colour-sort games for about three weeks before we both noticed she'd burned through it entirely and was getting ad-walled every two moves. So she rebuilt it. The rules are simple — tubes of mixed coloured balls, one move = pop the top ball, drop it on an empty tube or a tube with the same colour on top — but the puzzle structure scales gracefully from "a kid can solve it" to "you need to plan five moves ahead."

The strategy that took her from intuition to consistently solving the hard levels: always keep one empty tube available. Beginners burn their empty tube on the first move because it feels productive; experts treat the empty tube as a temporary buffer for the colour you need to dig out from underneath. Also, never pour onto a single ball of the wrong colour just because there's room — you're trapping that ball and the cost compounds.

Why this format is so good

It's a perfect-information puzzle with no luck. Every level is solvable in a fixed number of moves and the optimal solution is reachable by pure logic. The hundred levels here aren't auto-generated — they're hand-picked from a generator and then ordered by Josie's playtested difficulty curve, so the ramp doesn't have weird spikes. If you like relaxing logic puzzles, Strings on the site is the word-puzzle equivalent.