Browser-based multiplayer games are a great way to have fun with friends without the need for downloads or powerful hardware. Here are some of the best options:

1. Agar.io – A simple yet addictive game where you control a cell aiming to grow larger.
2. Slither.io – Similar to the classic Snake game, but in a multiplayer setting.
3. Skribbl.io – A fun drawing and guessing game, perfect for virtual hangouts.
4. Krunker.io – A fast-paced first-person shooter with simple graphics.
5. Cards Against Humanity Online – The popular party game adapted for online play.
6. Gartic Phone – A hilarious combination of telephone and Pictionary.
7. Codenames Online – The popular word-guessing board game in digital form.
8. Chess.com – For those who enjoy classic strategy games.
9. Powerline.io – A multiplayer version of the classic Snake game with power-ups.
10. Tetris Friends – The classic puzzle game with multiplayer modes.

These games are easy to access, require minimal setup, and can provide hours of entertainment with friends, regardless of their location.