i'll go with translated (or soon to fully be) ones, assuming the majority of the userbase is not able to read japanese
1. Subarashiki Hibi -The best (soon to be) translated title, gives by itself a wide range of different experiences by being a complete thing at the same time-
2. Cross Channel -Even if the translation is apparently bad, there's still so much content to be found here. The best character study i laid my hands upon-
3. Muv Luv series -Second only to Cross Channel for character development (even though only Takeru is really well developed this time) and mixed with some strong plot and worldbuilding, to be compelling even if you don't value characters much (Alternative)-
4. Sekien No Inganock -Outstanding worldbuilding with scenic portions (apparently the translation ruined this too). Repetion makes this magic -
5. Forest -Arguably the most confusing and weird thing you will read in your life-
6. I/O -Arguably the second most confusing and weird thing you will read in your life, this time with really strong Ghost in the Shell vibes and all around strong worldbuilding-
7. Umineko no Naku Koro Ni series -Quite a good "deconstruction" of the mystery genre, if you want to say so. Prose falls short occasionally, but the amount of content is pretty overwhelming-
8. Rewrite -Terra is the babies' version of Cross Channel. Some parts of the game are compelling and rich in their own right-
9. YU-NO -The epilogue is really what i would call mindblowing and the point & click "minigame" for the first part of the game makes it exciting, to an extent. Not to mention it aged pretty well, considering how old is it-
10. Sharin No Kuni -Just a good story all around with a great plotwist-