I love achievements. Even though my wife says the greatest achievement I have ever unlocked is “most hours spent in front of glowing screens” (that was for Vidmaster: Endure in Halo 3: ODST), I still really enjoy trying to “achieve” these meaningless rewards. It makes me wonder though, have achievements changed how I play games, or was it me who changed?
An example: in Left 4 Dead, once I finished the Expert campaigns, the game began to be less fun. It was okay to run through a campaign, but with no sound effect at the end of the tunnel, I found it less exciting. Same with ODST and the Firefight maps: will I ever go back and play them after I’ve unlocked the achievements? Firefight is a mode I could potentially have seen myself playing endlessly, but I know that thanks to the achievements, I’m not really gonna want to go back after I finish the 200Ks. If those achievements didn’t exist though, I might just keep playing to keep trying to beat my top score. But since achievements arbitrarily define these “top scores” in a lot of games, it takes away my inner desire to beat myself because I know what mark I have to get to to prove to the world my skill.
When I was a younger gamer, I just use to play games over and over because I loved them. I must have beaten Super Mario Bros. 3 like 6 or 7 times, and gotten to the last stage a bunch of other times as well. I used to race against the computer in Mario Kart 64 just for fun (though some of the shenaningans the computer pulled in 150cc drove me nuts), and I even played through the original Halo multiple times just for fun. Nowadays I can’t see myself doing that anymore. It’s partly because I don’t have the time, but it’s also because once I get all the achievements I want, I don’t have the motivation to play anymore. The only exception is multiplayer games I love: Halo 3 and Modern Warfare took up hours and hours of my life and I never really wanted to stop.
I guess in a way achievements made it easier to fit my gaming habits into my changing life habits. Now that I have goals in games to strive for, I can budget out the amount of time I’ll need to play, and that way I can balance my time better. It’s not as “pure” as when I was a kid, but let’s face it: I’m not a kid anymore, and I have responsibilities that are much more important than beating games 50 times. Instead, I can just focus on the achievement for beating a game twice and then go to bed! 
