I tend to get completely hung up on one game with a lot of replay value for years at a time. Back in the day, it was Red Alert (the first one) with an insanely modified rules.ini file: Super tanks, crates aplenty, ten times building speed, and multi-hour epic battles that a few times culminated in my friends and I seeing who could build Tesla Coils close enough to the other's base to fry his stuff without risking units.
Then there was Total Annihilation and Kingdoms--the gameplay of original TA was far better than Kingdoms, but fan-made addon packs made both even more fun. I like modding stuff to see how far you can take it, and if you're just playing on your LAN with friends, why not toss all the rules out the window?
Lately--okay, for the last 5 or 6 years, I've had a low-grade WoW addiction. I justify it in that it costs as much a month as one movie ticket, and I can play as much or as little as I want. Sometimes I don't play for weeks on end, then some weekends I sit at home and kill dragons on the internet for hours and hours. Since you didn't ask, here
's the little guy I have way too many hours invested in.
One of my friends works for Giant Bomb/Gamespot and he's a former game writer and producer, so he's constantly telling me about the new hotness, which I rarely have interest in. I don't even have a Steam account. But I'm at least a little versed in what's out and big because of his chatter.
Consoles? Molest me not with this pocket calculator stuff.