Well old titles that are on Steam have been ported to WebAssembly... and keep in mind these are just straight ports with little to no compression or asset fetching to reduce the file size and load times.

Curse of Monkey Island: https://personal-1094.web.app/scummvm.html (press esc key right away upon load to skip straight to playing)

Baldur's Gate 2 demo: https://personal-1094.web.app/gemrb.html

Diablo demo: https://d07riv.github.io/diabloweb/

Humongous Arts games:

Spy Fox in Dry Cereal demo: https://thatgamedev01.itch.io/spyfoxindrycereal

Pajama Sam demo: https://thatgamedev01.itch.io/pajama-sam-3