Brutes is a FFA punching game. Pound your enemies with your fists till they die, soak up the orbs they drop to level up, become bigger and a lot more powerful, and use power ups to give you the edge against bigger enemies. But watch out for the really big enemies.
Move around with WASD, and punch with the left mouse button. Hold for a more powerful punch that can knockback and stun. (Plays better with a controller.)
Smash enemies into little bits and then use those little bits to level up. You can also gain little bits from attacking special props in the environment, as well as a few NPC critters.
Be opportunistic. If two players are already duking it out, hop in there and finish them both off. Or grab a bomb if there's a big melee and make an even bigger boom.
Run. Whoever's topping the leaderboard can probably stomp you dead if they get close enough to you, so don't let them.