Not so much a web game as a web game development environment, turtleSpaces uses the simple Logo teaching language to allow users to create 2D and 3D art, animations, models and yes, games!
I recently built an arcade/puzzle harvesting game called HARVEST MOVE playable in your browser (On any device with a keyboard) on itch.io. The link : https://jslegend.itch.io/harvest-move
I used the kaboomjs library which is pretty easy to use.
You can check out this fully-commented listing of a pilotwings-style game here: https://turtlespaces.org/weblogo/?pub=182
The backend is written in Golang and compiled to WebAssembly, while the frontend is Javascript.