Depends on the context, really. If it's a professional gig, then you got payed (and it's up to the owner of the game to press charges).
If it's a rom hack, then there's not really anything you can do about it aside making sure your (combined) translation got enough publicity to ensure it originated with you.
I've had a...perhaps similar incident. Or not, depending on the context.
Anyway...as a member of a BDSM scene, I once wrote a short poem that made fun of the clumsy/stupid/bullying way some tend to think courting ladies is supposed to be (basically: some think abuse is okay if you're into BDSM. Just...it's not).
There was a musician on that scene, so I offered him the text in case he could use it somehow. Less than a day later, he got himself a local (site-only) hit. Not really sure how well it fared once he got it on youtube, but I didn't mind (I gave it to him, and he credited my nickname even in the song
).
So...fast forward a year or two. One of my friends tagged me for something: someone on another continent (US? I honestly can't remember) had shared something with the world. Except...it was a large part of my poem, translated to English. Quite good, I had to admit (it didn't just rhyme but it was altered to keep the cadance/rhythm that usually gets lost when you do a normal translation).
Nonetheless, she claimed to be the original author. Claimed never having heard my version nor the youtube version that originated years earlier. When I pointed out that wasn't so, she brushed it aside saying that it could be a coincidence.
Granted, it wasn't that long of a poem (20 lines or so? hers was about half), but no fucking way she happened to just come up with that (especially since she had almost no other creative outlet on her profile page).
Wasn't much I could do, nor that I wanted to do. I would've easily granted her the full text and credit for the translation. It's just sad that she wanted to pretend she was something she wasn't.