Normal highschool life

[Jaweh]

Hello! Im new here. But can anyone recommend me any game with romance that has to scifi thing going on that is set in highschool theme. Respect! 

[GXOALMD]

It's a little bit more mystery than sci-fi, but World End Syndrome might be a good pick. https://vndb.org/v22181

Additionally, while I absolutely do not recommend it, on paper Sunrider Academy fits what you're looking for nearly perfectly.  If you like resource management games, then you can probably get more out of it than I did, but if not then you should skip it as there is very little visual novel to it. https://vndb.org/v16221

To end on a higher note, Little Busters is a pretty good choice.  Chances are many of Key's work will be in line with what you're looking for, but I'm pretty new to their VNs so this is the only one I can speak for.  It also is a bit more mystery than sci-fi, but given the other aspects you're looking for it's probably the best choice of the one's I've listed. https://vndb.org/v5

[onorub]

^From the op title, i'm pretty sure he meant "no sci-fi thing" when he wrote "to sci-fi thing".

I guess vanilla fluff like Fureraba or Noble Works might do the job for you? (Noble Works has very light action, though)
If you don't mind yuri, the best thing i can recommend is the Flowers series.

[GXOALMD]

49 minutes ago, onorub said:

^From the op title, i'm pretty sure he meant "no sci-fi thing" when he wrote "to sci-fi thing".

Oh, if that is the case then the options I can suggest are much more limited.

Loca Love is definitely romance only so it might be a good choice.  I haven't actually gotten to it yet myself, so I don't know how relevant the high school setting is (but the characters are high school students). https://vndb.org/v23067

[r0xm2n]

* Katawa Shoujo . Really good setting, and the writing has a lot of respect for it's themes. This VN is free too.

* Fureraba . A bit silly, VERY comedic, and very cute waifus.

* Wagamama High Spec . Also very lighthearted. Like Fureraba, this is mostly "dating high school girls".

* Princess Evangile . Lends more weight to it's high school setting then most VNs. Quite a lot of comedy, has a bit of drama.

* Kono Oozora (If my heart had wings) . Has a focus on aviation. A pretty light hearted and feel good VN. Get the latest fan patch....

* Sakura Sakura . The point of this VN is it's comedic love triangles, and hilarious banter between the characters.

* Muv-Luv . Technically, the first entry in the trilogy, Muv-Luv Extra, is a pure high school comedy setting with a very fluffy cast. It's later entries (Muv-Luv Unlimited, and Muv-Luv Alternative), that adds sci-fi elements, and drama (lots, and lots of drama).

 

Now if you don't mind more drama, emotional punch, and (possibly some light supernatural elements)......

* Grisaia no Kajitsu . A unique high school setting. It's writing is awesome, humor is 10/10, characters are quite colorful  . It does ........ get particularly dark at times though (especially THAT one flashback)......

* Clannad . A KEY VN, which typically means a lot of heart-string pulling. Lots of themes about friendship and family.

* Little Busters . Another KEY VN. Has that real "enduring bunch of best friends" theme going for it. The soundtrack is particularly good (imo). The minigames during the common route can be fun.

* ef - a fairytale of the two . It's art and soundtrack are particularly good. Some of it's themes are ......... rather unpleasant......

[littleshogun]

As foor the recommendations, I guess you can try both of HatsuKoi and Hoshiori. If you want more, there's Daitoshokan and Noble Works. There's more on the category here, but I guess it should be enough for now. I hope my recommendations here will be helpful to you.