This reminds me a lot of what I was doing at my job. I work doing tech support. I was on the midnight shift. Almost all the calls that we'd take would be concentrated in the first hour and last hour of our shift, giving us about 5-6 hours of sitting around doing nothing some nights.
I never gamed with my coworkers, as they wouldn't have liked it. I did play a lot of MMORPGs though, mostly City of Heroes. If a customer called, I'd immediately stop playing and would often get myself killed in the game because of it. Still, I didn't care, it was great to have something to occupy the multiple hours of time I had free.
Of course, I was discovered by a manager who dropped by much earlier than they normally do and told that since they couldn't trust me to do my job, I'd be moved to the day shift. So, instead, I spend all day long posting here and hiding this web page from any managers who walk past.
Not sure if there is a lesson here at all...other than...don't get caught.