There is already a game called Solstice from 1990. Why does this game use the same title even though it's a completely different game?

Yes, let's auction off the entire English dictionary to publishers who can afford it until any new game not from them can only use random alphanumerics for a title.

It's bad enough "Cataclysm" and "Civilization" is trademarked (in itself a blatant violation of USPO's own regulations, but who cares when there's money to be made...)

The point is that there is a classic game called Solstice (and this site is called Good 'Old' Games, and is supposedly dedicated to classic games), and instead they host a modern 2016 game with the same title instead of a 'Good Old Game'.

Makes sense, but I can't even find a review for your game. "Solstice game review" on youtube: NES, NES, NES, Red Solstice, NES, Solstice Chronicles, Red Solstice, Red Solstice, Red Solstice, NES. Solstice is too generic of a name to stand out in a search engine unless it's massive. It's competing with movies, tv, an actual solstice, and other games. Only find it when I search Solstice visual novel.

For a game that goes out of it's way to adhere to some perceived modernity with your story telling, you are unaware of how a modern search algorithm works.