The Internet Arcade, from the Internet Archive:
The Internet Arcade is a web-based library of arcade (coin-operated) video games from the 1970s through to the 1990s, emulated in JSMAME, part of the JSMESS software package. Containing hundreds of games ranging through many different genres and styles, the Arcade provides research, comparison, and entertainment in the realm of the Video Game Arcade.
They have a number of classic games in there ( Defender! ) along with lots of titles I’ve never seen before.