My mom wont let me buy an m game as long as i live in her house, how can i change her mind about that? In my opinion the game shouldn't be rated M.

The M rating is very justified, it's a very bloody and gory game.

The best thing to do would probably be to talk about all the things you can do in the game besides shooting the head off.

Try to compromise with your mother, offering to do things around the house.

Ok thanks guys

Once you turn 17 (in the US) or 18 (everywhere else) you can buy it yourself.

But I assume you are not that age.