The man who gunned down five people and wounded 16 in an Illinois classroom rampage was a loner who preferred studying to partying and was obsessed with an ultra-violent video game, dormitory mates said yesterday.

"He played a lot of video games, especially Counter-Strike, really loud," said dorm mate Ben Woloszyn, 24.

In the game, players use imaginary money to buy shotguns, pistols and other equipment they need to move around an imaginary world in which they're constantly under threat of being killed by roving terrorists.