Unlimited is Classic without the daily limit: it deals you a random Clash Royale card, you guess it using the same seven-column comparison, and the moment you solve it you can start another. It exists so you can learn the card list and practise reading the grid without spending your one daily attempt.
The board, the seven attributes and every colour rule are identical to Classic — green for an exact match, yellow for one step away on Elixir or Year, two on Arena, or a partial overlap on Target, and arrows on the number columns. What Unlimited does not have is consequence: the card is chosen at random rather than drawn for the day, the round is played entirely in your browser, and nothing is reported to the server.
This is deliberate and worth being explicit about. Unlimited results never touch your win streak, your statistics or the Classic leaderboard, because a practice mode you can replay indefinitely would otherwise be an obvious way to inflate a ranking. If competitive standing matters to you, the daily Classic puzzle is the only thing that counts — Unlimited is purely a training ground.
Use it to build a mental map of the awkward columns. Arena is the attribute most players never learn, and a few dozen practice rounds will teach you roughly where each card sits far faster than the daily puzzle can. It is also the right place to test opening guesses: play the same first card twenty times and you will quickly see which one splits the field most evenly. Because it runs locally, it keeps working with no connection.
No, never. Rounds are random, played locally, and are not reported to the server in any form.
As many as you like — there is no daily cap and no cooldown between rounds.
Yes. It runs entirely in your browser, so it keeps working without a connection once the site has loaded.
Yes. Each round draws at random from the full card list, so repeats are possible.