NO CARTRIDGE
Pick one from the shelf. The emulator loads on first play, so give it a few seconds. Press F11 inside the game for fullscreen; the gear icon has controls and save states.
Idle
Game Boy Advance, NES and Nintendo 64, played in the browser.
python3 -m http.server 8000 in this folder and open
http://localhost:8000. Dropping in your own ROM file still works.
Pick one from the shelf. The emulator loads on first play, so give it a few seconds. Press F11 inside the game for fullscreen; the gear icon has controls and save states.