Like a lot of people have said so far, this is a great demo and has a lot of potential! You put it up as an alpha so I won't dock your score for something that hasn't been implemented yet.
*Good art. Roselyn is so pretty! So is Alison!
*Witty dialogue (It was their reflection the whole time XD )
*Not too easy. Challenges with puzzles here and there (con as well...)
*Good music, really helps set the feel. Really nice selection!
*Multiple themes. Spacey, but then it uses Medieval theme... I like it, and am excited to see the themes on the other planets!
*Good characters. I felt a good relationship with Max, he was more than just a generic "helps-you-get-laid" stranger with no story. Same with Roselyn, and even Amber. Protagonist seems a bit cocky, just don't go overboard and make him a douche and you'll be okay ;3 Can't wait to see Alison's story unfold!
*First off, the fucking riddles. Some weren't bad, like a stick being sticky or the one about tomorrow, but "seconds" in a year? Second what, second day? Some of them were a little too obscure I think, maybe have 3 tries for each time you start the riddles? So instead of taking 5 days it might take 2-3, going from frustrating-past-the-point-of-fun to legitimately-challenging-and-might-fail-a-lot-but-not-too-bad, y'know?
*On that note, I'd recommend leaving a bit of extra room to get a good ending. The way you have to cut it down to the wire left me with 1 spare day the next time I played, and that was when I did everything as I remembered to get the good ending. As it is, you have to know every single detail to get the good ending (which there's nothing bad about, just give us a bit of room to make mistakes in the final version please).
*Similar thing with Roselyn's quiz. I read all the text in these games so I don't think the questions you asked were at all unfair, just how I couldn't be sure which one or two I was getting wrong (thanks Zedoc, I cheated XD ).
*When I need to lift the boulder, etc. then telling how much strength I need would be nice. Quick fix, not too bad.
*Sex scene was okay, good. A little too short I think, that might be part personal preference though.
*Maybe add an easy/normal/hard choice for how many days the player has?
*I wonder if there'll be more items for an inventory, or just the rubber ball?
*Maybe go further with Amber as a possible girl/easter egg? She's cute! :3
Overall, very nicely done. I'm very excited to see the next install(/s) and finally the finished game! :D
Also, what' the piano song that plays during Roselyn's quiz? It's gorgeous, and may be the best scene-song match in the game!