Hadn't occurred to me before but just did a quick interweb search for 'Solstinox' and...

...there's a game that was made with the Unreal Engine at the Université du Québec à Chicoutimi called "Solstinox".

And also a game called "World's Nicht" being developed by a company called "Solstinox Games".

And there's also apparently a Ground/Dragon Legendary Pokemon called 'Solstinox'.

It is the master of the Season Quartet.

Does this legitimise the name or make it 'already taken'? :)