What game genre do you think one little mistake matters most?

I think a 1 little mistake can fuck up pretty much any RPG for me (i.e. Oblivion's harsh difficulty due to the slow leveling).

This also doesn't just have to be limited to developer mistakes, this can also extend to player mistakes.

I disagree about the RPG thing.
 
A good RPG developer will take your "mistakes" and make it part of the experience rather then let it take away from it. 
And there are a lot of RPG games that have interesting flaws that end up working out in the long run (like Fallout 3's janky-ness)
 
Fighting games however...one fuck up can be drastic

Bad AI in fighting games. I don't want to rely on multiplayer to have a good time with any game, but so many fighting games just completely fail with their AI. The only game that routinely gets it right is the Virtua Fighter series - I was also very impressed with Soul Calibur IV's AI until I got to the higher difficulty stuff which gets completely cheap and obnoxious. Street FIghter AI isn't too good either, and Tekken AI plays pretty robotically as well. Pretty much every Mortal Kombat game becomes unplayable to me because there comes a point where the AI is so unbearable. The SNK stuff on XBLA has also been pretty bad.

" Bad AI in fighting games. I don't want to rely on multiplayer to have a good time with any game, but so many fighting games just completely fail with their AI. The only game that routinely gets it right is the Virtua Fighter series - I was also very impressed with Soul Calibur IV's AI until I got to the higher difficulty stuff which gets completely cheap and obnoxious. Street FIghter AI isn't too good either, and Tekken AI plays pretty robotically as well. Pretty much every Mortal Kombat game becomes unplayable to me because there comes a point where the AI is so unbearable. The SNK stuff on XBLA has also been pretty bad. "

" @EliasT:  I completely realised the irony of the statement, but to elaborate it's not so much about comparing skill and more comparing how they feel to play against. My biggest problem with AI in a lot of fighting games is not the AI is worse than a human player but that the AI often becomes incredibly cheap at higher difficulties. I know it's not a view a lot of people share and understand, but as someone who has an appreciation for fighting games, an intrinsic dislike of online multiplayer and a complete lack of friends, I care far more about AI than other people. "

Any mechanical issue would destroy a fighting game.

" Any mechanical issue would destroy a fighting game. "

This.

I dont think saying RPG's need to be perfect or they are broken is appropriate. It entirely depends on the RPG you are playing, one small almost noticeable mistake in one game could very well break the next and vice versa.

Infact I think this applies to almost any genre, however EpicSteve does have a point with fighting games.

Open world games and a lack of variety with the gameplay.

One badly designed stealth or escort mission in a regular action game can ruin a whole experience for me.

FPSs.  
 
They are generally set with a limited number of commands. Generally the necessary.  
 
If one fails, the game fails.