The only game i've been addicted too, like really addicted too was Counter-strike that game is soooo goood
I don't know what it is but when you play it online with friends and get good at it its just seriously addictive and fun! I'd still be playing it if my pc could take 1.6 but it can't so
Another game i got addicted to was Ragnarok Online which is a fun game but sucks due to its Pay 2 Play feature.