I'm a crazy person because I decided to invent my own language for the game I'm working on. Incidentally, that's part of why I haven't posted a lot recently... because most of what I've been doing is not particularly visible or not very novel (like showing off the 100+ weapons I spent weeks illustrating).
The language is basically still an English cipher. My translation system right now is a simple regex that swaps out English words with words from the Inimnth language (using pairs in a JavaScript dictionary array). You can see in red/bold all the words it can't translate yet because I haven't described Inimnth equivalents for those words yet. Also the pronunciation is Latin-ish but I don't really care.
I don't think I want to invent a separate grammar system. That's more work than worth as far as I'm concerned. Originally I only intended to use the language in a limited extent, basically just proper names for certain locations and weapons in the game. But now I want to extend it quite a bit further. I know it looks like a lot of red in the picture above but actually I have 916 words defined in the language already. I know for Game of Thrones they made about 3000 Dothraki words, so I'll probably stop somewhere in that neighborhood.
Something that's been built into the game from the beginning is that you can brew potions at cauldrons (bonfires basically). The list of potions the player is capable of brewing herself would grow throughout the game, though I hadn't yet figured out how the list would grow. I thought maybe you can buy recipes at one of the stores in town. But now I think it'd also be neat to find ancient recipes from this alien race for additional potions, and then to have to go into town where the scholar is and get the recipes translated.
And if I can come up with other uses for things to find that need to be translated I will. Note that this will be relatively automatic... I'm not expecting most players to actually learn the language and translate texts themselves, though that of course is an option for any extremely devoted fan. I just like world-building and enriching the lore!
When you said "invent my own language" for some reason my mind went to "invent my own programming language" and was about to freak out.