Kata Shift
Find the rule. Then let it go.
How to play Kata Shift
Sort the top card onto the reference card it belongs with. The matching rule is hidden — correct-or-wrong feedback is your only clue.
After a streak the rule switches silently. Your first miss after a switch is free; keeping on sorting by the old rule costs a life. Tap a card or press 1–4.
What it trains: hidden-rule card sorting
Kata Shift is built on set-shifting, the skill probed by classic card-sorting tasks in cognitive research: infer a sorting rule purely from correct-or-wrong feedback, exploit it — and abandon it the moment it silently changes.
The hard part isn't finding the rule; it's letting go of one that just stopped working. Clinging to an outdated rule (perseverating) is exactly what the game punishes.
Does brain training work? →Scoring & progression
Runs are endless: you climb levels until your lives run out, and scoreboards track the highest level you reach. Strong runs feed your belt progression in the logic discipline — from white belt toward black — and your place on the global leaderboard.