Lair, too human, haze and few others I forget mostly are considered flops.
If so many people consider something a flop, most likely it is (and I'm saying many many people, not just one person doing a list) because that means there was a very high expectation of the game by a lot of people (again not just one person). Expectations that the game will be awesome and have awesome sells, then there is something that is out of the community hands that adds to the flop factor- development costs. Of course if the game sells doesn't come reasonably close to the dev costs then of course it will be a flop. I think those 3 factors add to "flop".
If a game sucks + game sells awful + dev cost loss is really high = flop
Wii fit isn't no where near a flop, even though I find it boring.







