The app, step by step. The rules are on their own page; this is what you'll see and what to tap.
Someone deals a game and picks Okey on New game. Four is the usual table; two or three works too. The Rules step has your family's settings — leave them and you play the usual way. Say Deal me in; the table deals itself when everyone has answered.
At the top: the face-up tile, and under it the line that matters most — for example "Okey: teal 8 — wild this hand". Beside it, the stock and how many tiles are left. On your rack a wild tile carries a small ★ in its corner. The tile with a big ★ is the false okey: it is not wild, it plays as the okey's own face.
Every player has a pile showing its top tile. The one on your left is the one you can take from — on your go it's lit and says take, and tapping it takes its top tile. At other times, tap your own pile or your left's (when it holds more than one tile) to look through it; tap again to close.
Tap Take for the lit tile, or Draw for one from the stock. Then tap a tile on your rack and tap Discard. That's a go. Colour and Number over your rack sort it either way.
When throwing one tile away would leave 14 that are all sets and runs (or seven pairs), that tile gets a blue ring. Tap it, then Go out. The app checks your rack, so Go out only works on a tile that wins.
If you hold the other copy of the face-up tile, a Show button appears until your first draw. Tap it and everyone else loses a point.
When someone goes out, the hand is scored and the next one is dealt by itself. When the stock is empty you can still take from your left; tapping Draw on an empty stock ends the hand and nobody scores. Everyone counts down from 20; when someone reaches 0 the game is over and the highest score wins.