Games!

[artabria]

 Itchio has a lot of free games you can download and play. 

[LINK]

For something more old school, there's the Internet Arcade: "[...] 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".

[LINK]