Warhammer 40,000: Battlesector

Can be done in a hot seat multiplayer game with a 2nd controller. To make it easy set up a couple of new army lists with the Trygon in one and a few assault marine squads in another (on the main lobby screen under army management, press Y to set up)and sign in both controllers as the same profile on the setup screen. Once you start the match surround the Trygon with your marines and go to town. You can use your chainswords and grenades to damage it quicker but make sure the killing blow is done with your bolt pistols. Should take about 10 minutes