Standard 52-card deck, Ace high. You vs the computer.
Each player gets 3 face-down cards, 3 face-up cards on top of them, and 3 in hand. The rest is the draw pile.
Before play you may swap cards between your hand and your face-up cards: tap a hand card, then a face-up card. Then press Start game.
Who starts: whoever holds the lowest 3 in their hand (3♣ is lowest, then 3♦, 3♥, 3♠). If nobody has a 3, the lowest 4, and so on. 2s, 7s and 10s don't count.
Playing
Play a card equal to or higher than the card you're facing. You can play several cards of the same rank together.
After playing, draw back up to 3 cards while the draw pile lasts.
If you can't play, you pick up the whole pile, then you must play again (on the now-empty pile). You can't pick up if you have a legal play.
When your hand and the draw pile are empty, move straight on to your face-up cards. If the draw pile is empty and your play uses up your whole hand, you can add face-up cards of the same rank in the same turn.
When the face-up cards are gone, play face-down cards blind, one at a time. If the flipped card can't be played, you pick it up with the pile and then play again.
The first player to get rid of all their cards wins. You can finish on any card, including a 2, 7 or 10.
Stalemate (app rule): because you must play again after picking up, two players can get stuck passing the same card back and forth forever. If exactly the same position comes round four times, the game is a draw.
Special cards
2 = reset. Goes on anything. Any card can follow, and you play again.
7 = see-through skip. Goes on anything. It does not give you another turn. Your opponent plays next and must beat the card under the 7 (a King under a 7 means King or higher; an empty pile or a 2 under it means anything). Several 7s in a row are all see-through.
10 = burn. Goes on anything. The pile is removed from the game and you play again.
Four of a kind in a row on the pile (including four 7s) also burns it, and you play again.