Sorry if this was covered before and I missed it but wow.
https://archive.org/details/internetarcade

It appears various license holders have allowed the interenet wayback machine people at achive.org to setup an internet arcade archive of machines where you can play the games right in your web browser. There's over 135 games up there currently, not sure how this was all setup but it appears to have went up over the summer and it has cames from many major developers too.