This plays just like everyone's favorite family card game, but there are a few things to know to play it online.
The teacher assigns each group a group name. It can be anything, but if someone is playing it in another class and assigns the same number on the same day, there could be conflict, so at least a three letter or number code is a good idea.
On the first screen, each member of each group enters their assigned group name, number of members in the group, and their individual name, then hits "次へ ／ Next." They don't have to enter their real names, and if there are two kids with the same name in the group, they should enter different names (I think), e.g., Koki1 and Koki2.
On the next screen, members of each group select which order they'll play in. The player who wants to go first selects Player 1, etc. When all players have chosen, all are automatically sent on to the actual game.
Now it's time to start playing. At the top, players will see a banner announcing whose turn it is, using the names they entered in the set-up screen. The banner will be flashing for the player whose turn it is (flashing rate chosen to not trigger seizures). Below that are the Discard and New Card piles, and to the right a Pass button. When available, an Oh, No! button will appear. Below all that as a row showing all the other members and how many cards each has. And below that is the player's own hand.
When it's a player's turn, they tap one of their cards to play/discard it: a regular card if either category (e.g., color or number or skip, etc. like in standard Uno) matches the top card in the Discard Pile or a wild card. After a player discards, play automatically goes to the next player. Consequences are dispensed automatically for Skip (next player is skipped), Reverse, and Take Two (next player receives two cards and is skipped). If a player throws a Wild card, a pop-up asks them to choose a color. Invalid plays bring an error message and tone. If a player doesn't have any playable cards, they should tap the New Card deck. They'll receive one more card, and if they can play it, they do so; if not, they hit Pass to pass play to the next player. All of that is enforced: they can't take another card if they have a playable card, they can take only one, and they can't hit pass if they have a playable. When the first player wins, the game ends with a fanfare--the remaining players don't keep going.
Oh, No! ("Uno!") Button. This part isn't fully automated because I want kids to say it, not hit a button. When a player discards their second-to-last card, leaving them with one, play passes to the next player as usual. The next player can play normally. But while the next player is doing so, or considering options, a four second timer is counting down (to give the player with one card time to say "Oh, No!"). After the four seconds, for all the other players, the "Oh, No!" button is enabled. If the first doesn't say "Oh, no!", any other player can call them on it and hit the "Oh, No!" button. The guilty player is then given two cards. If the next player discards (finishes their turn) before anyone hits the "Oh, No!" button, the button is disabled and the guilty player has gotten away with it. If your students are going nuts on the "Oh, No!" button, here's a link to a secret version with that button removed.
Finally, the buttons on the bottom. Activites Index goes back to the main index, Card Game Index goes to, well, that. Start Again starts again with the same players (they get to choose a new order), and New Group starts again from choosing a new group.