The defenders always choose the card that gives them the best chance of winning tricks, given the layouts still consistent with the cards shown - they never give a trick away. Success percentages are computed over every possible lie of the missing cards, weighted by their real odds - vacant places and restricted choice included.

No. The missing cards stay consistent with everything played so far, but they are not dealt in advance: if you do not play the best line, they will lie in the way that stops you from reaching the target, whenever such a layout is still possible.

Taking the stated number of tricks in the suit. If one of your cards lowers your chances, the result panel shows the exact trick, the card that cost, how much it cost, and the card that was better.

A set of combinations each day (three by default), the same for everyone. Your first attempt at each is the one that is recorded - solved first try or not - and afterwards you can see the day's leaderboard and join the chat. Replaying later is free and does not change your result.

No. The archive calendar only opens the days you actually played - a day you missed cannot be recovered.

The Solver is unlimited for everyone. Practice and Survival each have their own daily allowance: 3 per day on a free account, 10 per day with Pro, unlimited with Master. The Daily is unlimited for everyone.

The complete strategy of that line, written out branch by branch: which card it plays next for every card the defenders can play, all the way to the end. Restricted choice and the odds of each layout are already taken into account in every continuation.

A line is a whole plan chosen in advance. It reacts only to the cards that appear - never to cards it cannot see - so it can lose in a layout that would be winnable if you could look at the defenders' hands. The percentages already account for this.

Yes. In the Solver the URL contains the whole combination - copy it and anyone can open the same position, no account needed.