If you’re feeling nostalgic, you can hop on over to EmuOS. It’s an online repository of old video games and older pieces of software that you can use within your web browser. EmuOS has popular older games, such as Pong and Pac-Man, and also has Quake 1, 2, and 3.
EmuOS has a few different skins to go along with its retro feel, including Windows 95, Windows 98, and Windows ME. EmuOS is part of Emupedia. The Emupedia GitHub page outlines its purpose:
The purpose of Emupedia is to serve as a nonprofit meta-resource, hub and community for those interested mainly in video game preservation which aims to digitally collect, archive and preserve games and software to make them available online accessible by a user-friendly UI that simulates several retro operating systems for educational purposes.