I go through phases with games. I'll get one, play it for a couple of weeks, and then never play again. The problem is that these things are so darn expensive. PC games or PS2 games, I've got better places to put my money than games. I do seem to play a lot of them, though.
I'll admit it: I'm a cheater. Cheat codes, patches, trainers... yep, that's me. It seems I will do whatever I can to make the game as easy as possible, thereby making it boring. It doesn't make much sense, really.
I don't really play many games at the moment, but when I do, they are usually the free Flash games that you find scattered across the web.
Another game I play regularly (if you consider it a game) is online poker. I play at ultimatebet under the username "everyone" so that when I win, it says, "everyone wins $1.50 with three aces."

I started playing for free, but then I hit a royal flush and won a real money jackpot of $5. I've since turned it into about $16 playing penny/two penny no limit hold'em, so I guess I'm not all that bad.
As for the best game of all time in regards to revolutionizing video games, I'd have to say the Grand Theft Auto series. It's not my favorite, though. Not only are they incredibly fun games, but they keep getting better with every release. They're definitely not games you want to play with kids, though.
Here are some of the other games I've played recently (in no particular order):
MTX Mototrax - A nice-looking dirtbike game. It's fun to ride a motorcycle for a while, but the tricks are completely unrealistic. This game lost its luster in about a week.
Pirates (the new one)- It's a pretty good game, but my poor little graphics card didn't fare so well. The gameplay seems to get very repetitive very fast. Sail your boat somewhere, sink other boats on the way in hopes that you defeat a famous pirate, and do some lame dancing. It kept me interested for about a week.
Need for Speed Underground 2 - This game was a lot of fun. The graphics are amazing, with nice reflections everywhere. But when it comes right down to it, it's the standard drive-fast-to-build-a-faster-car-and-drive-faster game. I played it for about 2 weeks.
Rollercoaster Tycoon (2+3) - Two was a great game. You could get a trainer that gave you unlimited money and unlocked the rides. I played the heck out of this game on my old P-200 (
with MMX Technology, you know). I picked up a new copy about 8 months ago at BestBuy for $2 (pricing error, I think), and the game is
still a lot of fun. RCT3, on the other hand, is awful. They changed it from 2d to 3d, and did a horrible job at it. To me, the game is barely playable.
SimCity4- Probably my favorite game of all time. It's got nearly everything, although there is certainly room for improvement. I'd like to see an "in-car" mode where you can drive around properly, instead of this awful overhead view that reminds me of the early GTA games. Of course, I think they need to wait for technology to catch up to their ideas. I've played all the SimCity games, and have liked them all.
The Sims 2 - Another good game that I still play. I really don't play it how it is meant to be played, though. I couldn't care less about the actual people in the game-- I like to build houses! I've got a neighborhood with about 10 custom houses. The all look great from the outside, but are not furnished or anything like that. I really just try to push the limit of what the game will allow for construction.
The Political Machine - Yeah, I got this one. It was fun for about 6 hours. Then, you realize that all you need to do to win is raise money faster than your opponent. Big surprise.
Tony Hawk Underground 2 - OK, I don't know why, but I like skateboarding games. I don't skateboard, and am not really interested in it, but for some reason the gameplay is great. This game is very well polished, and so it makes for some addicting gameplay. This one had my thumbs sore for about a month.
Mike