This game is incredible! Made in 3 weeks? Impressive, really... I have worked on several First-Person adventures inspired by Myst, and always tried to give them that kind of feeling, which is hard to describe and to create (you know, the "mysterious" feeling!). And Seclusion has done it very well! I loved it at every second. There are a few issues of course (can't change options settings anymore once you start to play, no save menu, etc... but it couldn't be perfect during a Jam). The rest of the game is just truly amazing.
The graphics powered with Unreal Engine are enchanting, mysterious and beautiful, with the nice atmosphere effects that improve even more the quality (mist, fog, colors...). I know that the creator has used existing assets from the internet (which is understandable in a Jam), but using assets doesn't make the success of a game, they have to be assembled in a clever way (level design): here he has been able to put them together very well in order to create a nice coherent floating island with several possible paths.
The audio too was great (I have not found if there was a music composer or if they were free musics from the internet, but they are well chosen!), and the sound design is efficient.
And most important: the challenge and puzzles is very nice: not too difficult for most players, not too easy for the others. The whole challenge still remains quite "easy" globally compared to other games of the genre, what I mean here is that I didn't need to rely on taking notes on a sheet of paper, and didn't have to ask for help (even if at a moment I thought I was stuck). I had to search well and think on my own, and it was always rewarding to find the solution of a puzzle. At no time I was frustrated. Of course there is place to improvement (the puzzle with the pipes didn't seem to me very logical from a realistic point of view: I mean, why would there be several branches in the same pipe to lead the steam to one sigle place? But it's not the point of this puzzle so it was still ok).
I noticed several references to Riven (the door in the dark, which in addition hides a secret passage behind). Really excellent, I had a great moment playing Seclusion.
The story is simple but well told through the papers to be found here and there. It took me about 30 minutes to finish the game. It will probably take an hour or two if you are not very good at solving these puzzles, but try, just try! Don't give up at the first obstacle in the first room: observe and think, try to find the possible interactions, and you will feel the joy of making progress in that kind of game/world.
A true gem that deserves some attention in my opinion, if you are not too reluctant to that kind of game! Looking forward to see more from the same creator. Keep up the good work!