There is loads of game experimentation happening on CodePen. I love that. People figuring out spriting techniques. People exploring gaming frameworks. People investigating gaming mechanics and physics. There are also some full-fledged games like Snake, Mine Sweeper, Flappy Bird clones, and Connect Four.
But then there are some really unique stand-out games that are as fun as anything I have installed on my phone! Here's a few:
David DeSandro's Cub n Pup
Setup Draw's faithful replication of Asteroids
Nathan Taylor's Platform Game
It's just an interesting detail that it's done entirely in HTML and CSS. The game itself is quite fun!
Jack Rugile's Futuristic Snake
M.Selman Yurtseven's Math Game
Matei Copot's Glitch Maze
Tip's Swine Peeper
Blaz Kemperle's Path Finder
Can't get enough? Here's a big Collection.