And Quake 3: https://thelongestyard.link/q3a-demo/
And Unreal Tournament: https://dos.zone/mp/?lobby=ut
There's also https://noclip.website/ which, while not playable, has hundreds of levels from dozens of older games that you can explore freely. Including Half-Life 2, with more accurate rendering than this web port (which seems to be missing many shaders including character eyes).
And Red Alert 2: https://news.ycombinator.com/item?id=45991853
Doom 3, smoother on Macbook M1 but it's too dark that I need to actually increase brightness on Firefox reliably. Is there a better solutions?
And CS: https://play-cs.com
And Tomb Raider
https://eikehein.com/stuff/sabatu
Fan remake of the levels to avoid asset copy, but it's a downstream of the original engine (and loads the original level files just fine), so the real game.
I vibe coded this for exploring levels in the original Deus Ex: https://dxwebview.pages.dev/ (https://github.com/addrummond/dxwebview).
It's a bit janky owing to the vibe coding, but the basic functionality works pretty well. You need the original game data files to use it.
Also The Simpsons Hit & Run! https://shar-wasm.cjoseph.workers.dev/