Bloob.io

Link: https://bloob.io
A hub for quick multiplayer word, strategy, and board-style games—try Wordrace, Battleships, Connect Four etc.

Gartic Phone

Link: https://garticphone.com/
A drawing-based game of “telephone” (pass the message), where you alternate between drawing and describing.

OpenGuessr

Link: https://openguessr.com/
Free and open alternative to geoguesser.
A game where you have to guess where are you located based on google streetview images.

Crazygames.com

Link: https://www.crazygames.com
A hub with tons of online web-based games

Smash karts

Link: https://www.crazygames.com/game/smash-karts
racing game with private lobbies

skribbl.io

Link: https://skribbl.io/
Online pictionary

Gidd.io

Link: https://gidd.io/
Play classic board games online with private lobbies

Wiki race

Link: https://wiki-race.com/
Race from one wikipedia page to anothe using internal links

Bomb Party

Link: https://jklm.fun/
Explosive word game were you have to type a word with the given letters to avoid exploiting

Trivial online español

Link: https://trivialonline.es/
Game of trivial with spanish questions

Tetr.io

Link: https://tetr.io/
Competitive game of Tetris online

Anime music quiz

Link: https://animemusicquiz.com/
Game of guessing the anime opening, with support for custom lists from the players MAL or Anilist