Phaser.js

Likely the best JavaScript 2D game engine as of 2023.Uses Matter.js as a physics engine if enabled. There's also an alternative (in-house?) "arcade" engine: photonstorm.github.io/phaser3-docs/Phaser.Physics.Arcade.ArcadePhysics.html but it appears to be simpler/less robust (but also possibly faster).

TODO any 2D first person examples a bit like Ciro's 2D reinforcement learning games?

The examples are present under: but note that that repo is huge, about 4.5 GiB on local disk, as is has tons of assets.

The demos also include a Monaco-editor based sandbox mode where you can edit code directly on the web and see the game update which is a really sweet addition.