I'm not going to bother with spoiler tags, since the title clearly says "when you have finished the game"
1) What puzzles did you like the best? Why did you like them?
I really enjoyed prying open the door in the Machine Room, simply because I am
sick of not having that option in other games. "What's that? You're a hyper-buffed space marine with enough explosives to level half a city - but damn, I don't have the key to this half-inch wooden door. Better not go this way." Not in Penumbra. Grab bar, ram bar in, SNAP goes the lock.
2) What puzzles where the hardest to solve? Why where they so hard and what kind of solutions did you try before finding the correct one?
Those God-damned laser tripmines. I'll give you the "set them off and you're dead anywhere" due to the shock wave, but they're at least a foot from the ground in-game. Evidently lying prone isn't something normal humans can do - or Philip has a really,
really big head.
3) How did you find the pacing in the game? Where there any particularly slow moments or some moments where too many things happened?
Pacing was
perfect. Much improved on the first episode.
4) How did you like the variation of events and gameplay elements? Could there have been more diversity or should there be more focus on the gameplay?
Similar to the above, I think you nailed it here. I would like to see multiple ways to solve the objectives - while you never get the feeling of being led around by the nose, you're definitely tunnel-visioned. Having more than one way to approach things would definitely entice me to play this again.
5) How did you like the characters in the game? Was their voices fitting? Was the voice acting good? What character did you like best / worst?
Clarence was quite good, and the disappearing door and end-hallucination fit perfectly with his character. Since there's only one other character, that would make the "worst" Amabel - like others have said, she's not nearly stressed enough given the situation. I understand the "stay calm" mentality she might have, but she should at least get a little excited about the prospect of rescue. Or murder, whichever comes first.
6) How did you like the ending?
The final stages felt a little tacked-on, to be honest. The green-light room, the same "generic brick #451" texture on the walls of the trials ... ugh.
Other comments
Do you guys need an English text proofreader? You've got more than your fair share of typos, and idioms or metaphors that aren't mixed quite right. Should I just search for and post those?