Xbox 360 Achievements, Great concept

I am sure all of you out there are familar with the Xbox 360 achievement system, and the gamerscore you are awared for these achievements. I really think that the achievement system is not getting the attention it deserves. Its an awesome system, that gives many players the extra initiative to get the most out of the game and earn the sacred gamerscore. Many games, sports games for instance are really skimping with the achievement systems, whilst others like Perfect Dark really make it to hard to earn all the achievements. There needs to be a happy medium somewhere out there. Out of the games I have played, I really have noticed Elder Scrolls IV: Oblivion to have a great achievement system. A achievement layout that is not impossible, but at the same not to easy. Yeah, I know, Oblivion comes up once again. And then you have individual achievements that are just plan stupid, IE G.R.A.W's World Champion achievement (Climb to the top of the universal leaderboard), which is literally near impossible.

Its a really good feeling, unlocking every last achievement in a game. Especially the more difficult achievements found in games. Proably the hardest achievements, I personally have earned were the surviving 1, 000, 000 straight and 10X Multiplier in Geometry Wars. I had to play for hours days just to get them. And when I did, what a feeling. Retail games can only have a total of 1000 GS (Gamerscore), whilst XBL Arcade games can have a maximum of 200 GS. So you can't scam your points off of small little arcade games, the enforced these limitations, or at least that would be the logical point.