Is it fine that LanguageTool tells me that 
?
This game is often called NFSU2 so my capitalized
For should be fine. Does LanguageTool suggest using a lowercase letter because usually in acronyms the articles are omitted but if acronyms are written in words the articles are written beginning with a lowercase letter? Because in this case would be NS but as it’s too short probably developers decided to make for “relevant” 
.