Turn studying into a game.

What makes it work is not the points but what earns them: every point here is a question answered from your own material, which is the practice testing the research rates highest. The game part is what gets you to do it for an hour. The Active recall page lists the papers.

In a world: XP, levels, HP, the next map when you beat a boss, a streak multiplier for runs of right answers, items from chests, and a finished world. Across worlds: achievements, daily goals, a day streak, titles, clothes and companions for your avatar, and decorations for the room in the study timer.

Yes: the games run in the browser on a phone or a tablet with on-screen controls, and there is an Android app. Progress is the same everywhere, since it is saved to your account.

If the material explains things in sentences, yes: medicine, law, history, biology, economics, psychology, languages, certification manuals. It is weakest on pure calculation and on books that are mostly images or tables.

A timer rewards minutes, whether or not anything went in. Here the rewards come from answers, so they measure what you know. There is a study timer too, free, with its own room and XP per block, for the days when sitting down is the hard part.

Playing is free: the public worlds cost nothing and never expire, and every premium world has a preview (5 battles, 10 Tower Climb questions and 10 mini-game questions, plus the flashcards of its first maps). Your own book takes a book-to-game credit; Lifetime Pro is one payment that includes 3 book-to-game credits and opens every world in full. No subscription.