As everybody else here has recommended, Planetarian.
"Please don't split heaven in two" BAWWWWWWWWWWWWWWWWWWWWW
Anyways, in other news, I continually find myself reminded how spoiled I am that my first three VNs consisted of Digital, Princess Waltz, and Yume Miru Kusuri. After experiencing three EXTREMELY high quality VNs as my first taste of the VN world, I find it impossible to sit through a lot of second rate VNs.
Example, Wind: A Breath of Heart. Don't hate just yet.
First of all, I will admit it's partially my fault for not getting the all-ages version. However, I was under the impression that, like YMK, the story would manage to smoothly insert the sex scenes in a logical, and unforced way.
WRONG. SO FUCKING WRONG. The sex scenes seem to be tossed in there just at the most random fucking moment just to have a sex scene. I get the feeling the authors really didn't want to put one in, and only did so in order to get more sales from the prepubescent crowd. It's just so fucking forced and unecessary and RAAAGH.
Also, the storyline is just WEIRD. They never explain these power things. (They might. I dunno. I stopped when I got my first sex scene just because that's how much I raged.)
Also, this is just a personal thing. I HATE HATE HATE HATE VNs that try to emphasis one heroine over another. I am of the opinion (Primarily, once again, thanks to Princess Waltz and YMK, partially Katawa Shoujo, who's demo got me into actually reading [As opposed to just fapping to] VNs in the first place.) that all heroines should be treated as equally important. When one heroine's route is considered the "true route" or some shit like that, IT PISSES ME THE FUCK OFF. This is the primary reason I haven't played Ever 17 yet, despite everybody being "ZOMG SUCH A GREAT VN". I don't give a shit. Just the fact that I know that Coco's route is treated as some sort of fucking "true route" annoys the shit out of me.
ALL HEROINES SHOULD BE TREATED EQUALLY.
Anyways. Continue on your merry day.