Swingers
Swing with friends to rack up the most damage to city infrastructure.
Genres
A party video game is built around player-to-player interaction, with simple controls that players of any skill level can pick up. Most are collections of short minigames played in quick succession by several people in the same room. The core loop is to play a round, tally points and start another. Mario Party (1998) and the Jackbox Party Pack series (first released in 2014) are examples.
Party games need local multiplayer: several controllers on a shared screen or, as with Jackbox Games, phones used as controllers. The code has to handle several inputs at once, run many small minigames with their own rules and keep a running score across them.
In a browser, the Gamepad API reads several controllers on one machine, each with its own index, and phones can join as controllers by opening a page that talks to the game over a WebSocket.

Swing with friends to rack up the most damage to city infrastructure.
Race around a board and win chaotic minigames with cute AI-themed characters
Shove cute animal fighters off the arena in fast, chaotic 3D brawls.
Charge and clash with penguins to knock rivals off a crumbling hex ice arena.
Steer a giant bird whose shadow paints the desert; biggest territory at nightfall wins.
Play party mini-games with friends, using your phone as the controller.
Sing a Renaissance motet together with other players in a shared choir.
Fill a bingo card with your own predictions and play along as events unfold.
Team up with friends in chaotic co-op, each player using their own key
Help or sabotage a shared Everest climber alongside thousands of other players.
Shove rivals off a cosmic arena platform in chaotic multiplayer brawls.
Counted from the 11 games above. A game can name more than one tool or genre, so a list can add up to more than 11.