Hey, come on! Don't be so incredibly hard on yourself! There's nothing wrong with your brain, it wasn't made for pixelhunting adventure games. You're a perfectionist, that's all.
Need a hint? Ask us. I'm pretty good at giving subtle or not so subtle hints, if I say so myself.
You decide the level of our hints.
I don't remember that bug. I'll see if I still have a save just after the key, but the chapters are not all that linear so you may have to redo stuff, which is frustrating and boring.
