There are two things that will kill the enjoyment of a game right off the bat.
The first is localization -- if you're going to translate to another language, get someone who is NATIVE to the tongue to help you! Terrible grammar and mislabeled items really grate on my nerves. It IS possible for me to overlook it and still enjoy the game if the story and gameplay are good enough, but it still really bugs me.
The second is a MAJOR gripe, and will actually invoke a feeling of hostility from me. Tasks that defy physics and could NEVER work in a million years, tasks that are so dangerous that you would literally DIE, and sheer stupidity in our tasks.
Let me give you some examples I've come across:
There is a glass dome with a lock about half way between the top and bottom. We're supposed to be able to use a magnet to move the key to the lock, thus unlocking it and getting us the key. First of all, why can't we just break the glass? Secondly, how on EARTH are we supposed to be able to, in reality, position the key EXACTLY right so that it goes into the lock? Not happening! Even if the lock was right against the table at the bottom, it would be INCREDIBLY difficult, if not impossible!
In one game we're asked to shoot an oxygen tank with a flare gun in order to get through a thin wall. Excuse me? There has to be a MUCH less dangerous way to make a hole in that wall... and besides, I don't think a flare gun would have enough power to break through the tank in the first place! This particular game was one I was really enjoying until they kept stretching believability to the breaking point -- this one example is just the tip of the iceberg!
As for sheer stupidity, we see that in a lot of games. Why can't I break that vase with the brick in my inventory, instead of filling it with water to get something to float to where I can reach it? I can forgive that, it's not that big a deal. When I'm asked to break a music box by cutting a rope that has an iron dangling from it, and letting it fall on the box... Well, that's just plain STUPID!
For one thing, why in the world would someone hang an iron from a rope in the first place, why would it be hanging over a desk and perfectly positioned over the music box, and why, if I need it so much, can't I just untie the darned rope? Maybe I can't get the knot loose, that's fine... but even more pressing, to my mind, is why in the WORLD can't I just break the darned box with the TIRE IRON I have in my inventory?!?
Whew~ Rant over. I feel a little better know