Portal 2 was a great game, and i loved the Co-Op, but the problem is that it's a puzzle game.
Now i say that because with the Portal 2 type puzzle games, it's the same thing every playthrough, you don't have anything to change that. Co-Op was AMAZING the first time through, but all the was lost on the second playthrough, becuase it's the same playthrough. Yahtzee put it best, when playing with a new person, either you're going to be angry for carrying the newbie through, or the newbie will get angry because you keep solving all the puzzles.
I think Deus Ex is a good contender, and i feel that some of the negative feelings come from the fact that it didnt live up to the original, but you need to stop comparing it to a game made 6+ years ago, and compare it to all the games made THIS year.
Now i say that because with the Portal 2 type puzzle games, it's the same thing every playthrough, you don't have anything to change that. Co-Op was AMAZING the first time through, but all the was lost on the second playthrough, becuase it's the same playthrough. Yahtzee put it best, when playing with a new person, either you're going to be angry for carrying the newbie through, or the newbie will get angry because you keep solving all the puzzles.
I think Deus Ex is a good contender, and i feel that some of the negative feelings come from the fact that it didnt live up to the original, but you need to stop comparing it to a game made 6+ years ago, and compare it to all the games made THIS year.