The word is used quite a lot by a genius scientist character named Gladstone Katoa, but I think other characters use it as well. The game was made by 2K Australia, and a lot of the voice actors have Australian accents. It also seems like they're probably using Australian slang, but never having been to Australia I can't say for sure. Some of the characters seem more English than Australian, but they're all in an absurd sci-fi setting on a fictional planet, so they aren't really of any Earth nationality.
To my American ears, this word sounds a lot like 'bro'. 'Bro' has a lot of connotations in American English, summarized a bit in this Wikipedia article. Basically, if you use the word 'bro' a lot, many will think you an uneducated fool.
It may be useful to note that Gladstone does not have a thick accent, and he's not pronouncing every 'th' as a 'v', he's just using this word a lot when speaking directly to the player, whom he barely knows.
Hearing a genius scientist say 'bro' over and over would be a bit odd, and therefore hearing Gladstone say 'bruv' over and over sounds odd to me. I'm wondering if this was intentional on the part of the game designers.
In other words, should Gladstone saying 'bruv' all the time sound incongruous, or would a native British or Australian English speaker feel that it sounded completely natural?