It seems that you're using an outdated browser. Some things may not work as they should (or don't work at all).
We suggest you upgrade newer and better browser like: Chrome, Firefox, Internet Explorer or Opera

×
Halo...
Faerie Solitaire
If the OP wants "serious games" (beyond Serious Sam, which is obviously the BEST suggestion) then maybe a proper ARG is for him/her.

Or you could check out the work of people like Jane McGonigal: http://janemcgonigal.com/

No, I had a crush on her brain and enthusiasm first!

But seriously, people like her are writing some pretty important stuff and it's cooler than fuck.

Here's someone else doing something similar: http://www.ted.com/talks/jennifer_pahlka_coding_a_better_government.html