Half Life and The Longest Journey.

try Avast...its the best anti-virus in my opinion. And its 100% FREE.

http://www.download.com/Avast-Home-Edition/3000-2239-10019223.html?part=dl-AvastHome&subj=dl&tag=button 

My favorite and also the most immersive game I’ve plaid has got to be Fahrenheit also known as Indigo Prophecy.