I want to clarify this right away: I’m not an achievement junkie. I don’t get an adrenaline rush from the distinctive bloop that accompanies the “achievement unlocked” message, and I don’t care about my gamerscore. Given those facts, it may seem strange that I have gone to absurd lengths to get every achievement in a small handful of games. These elite titles are the members of my 1000 Club.

Achievements aren’t meaningless for gamers like me. I have been known to obsessively collect knick-knacks, grind levels, and accrue percentage points toward total completion. I may not care about the gamerscore side of the equation, but I’m always looking for fresh goals and objectives that will give me an excuse to spend more time with awesome games. Getting all 1000/1000 points is mainly of symbolic importance; by getting every achievement, you have likely seen almost everything that the game has to offer…or at least the parts of the experience that the developer thought were important.

Doing this with every title I play would just make gaming feel like a chore. The members of my 1000 Club are the standouts that, for various reasons, inspired such obsessive loyalty from me that I was compelled to explore their every nook and cranny. Those things will be different for each gamer, so what makes you decide to induct a game in your 1000 Club?

Mass Effect 3 (Update: 4/24/12)

I wasn't sure if I was going to shoot for the full 1000 points in Mass Effect 3, even though I did for series' two installments. The game has a multiplayer-only achievement, which I normally have no interest in. However, I got completely hooked on ME 3's multiplayer mode, so a lot of achievements that would have required tons of single-player came naturally during the course of my online matches. Things like Pyromaniac (set 100 enemies on fire) and Overload Specialist (overload 100 shields) are easy to get with the waves of multiplayer enemies, and the ease of switching classes means that you don't need to do several full playthroughs of the campaign as different characters. As usual, beating the game on Insanity was the most challenging achievement, though I found it far more manageable than it was in Mass Effect 2. The only fight that really gave me trouble was the final duel with Kai Leng. I certainly died in other encounters, but none of them required nearly the number of retries as that one. The relative ease of the Insanity achievement has a lot to do with better design, but also with the weapon that comes with the From Ashes DLC, the particle rifle. It uses a cooldown system (like ME 1) rather than the limited ammunition of ME 2 and 3, so I didn't have to scrounge for thermal clips during the tough fights.
(Mass Effect 3 Achievements here) 

Final Fantasy XIII-2 (Update: 2/27/12)

After I finished Final Fantasy XIII-2 for review, I couldn't wait to start playing again. I know that may sound strange (especially considering my complaints in the review), but I mean it when I say it's one of my favorite RPGs in some ways (read: not the story). I didn't have a guide or anything when I played it the first time, so I was flying blind. However, I love optimization and being a completionist, so I was determined to do everything right on my second playthrough. Monster infusion, character development, fragment collection – I did it all, and the game has some great post-game rewards for people who keep playing. The achievements aren't really difficult, but they are time-intensive. For instance, you need to kill every monster in the game, including the high-end superbosses. You also need to spend way too much time (like, hours) with the truly awful slot machine minigame in the casino. My favorite part of the process was the Paradox Endings. These non-canonical "what-if" endings are reminiscent of those in the classic Chrono Trigger. Once you beat the game, you can go back to fight certain bosses that were previously undefeatable, and your reward is a brief scene outlining the (usually catastrophic) consequences. I just wish there were more than eight of them. Another highlight of the second playthrough is that because I already knew how terrible the story was going to be, I had no expectations, and had a much easier time ignoring it and focusing on the awesome mechanics. I hope they don't change to much on the gameplay front if/when another sequel comes out. 
(Final Fantasy XIII-2 achievements here)

Saints Row: The Third (Update: 01/23/12)

I was having such a blast with Saints Row: The Third that I was already most of the way done with the achievements by the time I decided to shoot for the full 1000 points. As you progress through the game, you constantly see updates about your progress toward various challenges and achievements, giving you the sense that you're making headway right from the start, and most of the things are fun to do anyway. For instance, I don't need any extra incentive to nail enemies in the nuts or jump into cars Dukes of Hazzard-style; I'm just going to do that for the fun of it. Getting every achievement isn't all fun, though, since a few of them are poorly explained or designed. Taunting gang members is a part of two achievements, but it's never clearly explained that it needs to be done to non-hostile gang members -- taunting in combat doesn't count. The worst achievement of the lot is the one for doing all of the vehicle thefts. These are the weakest tasks you can do in the whole game, since they just involve picking up a vehicle and then driving across town to drop it off. The catch is that you need to pick up a specific target vehicle; if the job requires you to steal a cement mixer, you can't just take any cement mixer. You need to grab it from the designated area on the other side of the city. I'm complaining now because the vehicle thefts were the last thing I did, but for the other 45 hours I spent in Saints Row: The Third, I had a fantastic time. I'm keeping my fingers crossed for a fourth.
(Saints Row: The Third achievements here)