Novadrome

Hounded is already unlocked, you just have to select it. Go to Arcade Challenge and pick your fastest (best grip) car. This one is a bit tougher than the other arcade challenge achievements. To become the 'Hounded' you have to pick up a blue orb on the ground. The easiest map to get this achievement is Nexus Allotropic Rim. Just turn left from the start and you will see 3 orbs on the ramp. Pick up one and don't get hit from any other players the rest of the round.