Quake live's "main menu" interface was web based and a NPAPI plugin was used to run native code. When Chrome dropped NPAPI support, Quake Live moved to Steam, using Awesomium for the web interface part. The game is now an unmaintained relic but there still an active community.

https://en.wikipedia.org/wiki/NPAPI

https://developer.valvesoftware.com/wiki/Implementing_Awesom...

You had to download a plug-in I think