PuntGames is a collection of games freely downloadable, with no DRM, no sitelock, no restrictions, and no garbage. Submit your games by emailing puntgames AT proton DOT me.
This method is the easiest. Go to the website and click on a game you want to play. It will then immediately open.
If you can access the repository, you can manually download the games and then play them locally on your own computer as HTML files. Most games should be available as .zip files, but if the game isn't, you can just download the entire repository through any method and then get the game from there.
You can do this, this works.
PythonAnywhere (outdated)