Hey,
Fritomaster, so how's your progress?
Personally I don't see anything particularly horrible in learning a language through video games. Granted, it's not the most rational way, but if it's necessary to tip your toes in, or maintain interest in learning, or if it's just a way to relax between reading boring grammar books, well, why not?
Of course, you should realize clearly that video games have a very specific slang, and it's likely that part of your 'new' vocabulary would be absolutely useless in real life. And the proportion of slang/obscenities is about 20 to 1 comparing to everyday speech. I played once a game recommended to me by my friend's son, a 10 y/o boy (most players were about the same age). Gosh! These little kids were vicious. And foulmouthed. And mean, lol. If I'd used vocabulary from this game in real life people would think I'm deranged.
But as long as you realize that and use your newfound knowledge wisely, it should be ok. Don't get discouraged.