HL2 EP2 + MMod Final Battle Neighborhood Watch (not actually triggering the achievement though)

Saving all the buildings in the final battlefield from destruction. Tactics to be used for achieving this: 1) To defeat the first strider announced to be coming from the sawmill, don't use the car, just pick up a Magnusson at the sawmill delivery teleport and walk towards the enemy for better Magnusson launch convenience You have to aim rather considerably above the strider's hull to get the Magnusson attached. 2) When you hear the second announcement of a strider from the watertower don't fall for it. Defeat the current strider and its escorting hunters, then drive to the sawmill, load your car with a Magnusson and TURBO to intercept the strider approaching from the cranes. That strider walks fast and leaves its pack of hunters behind, so you have to beat it in a race towards the next building, launch a Magnusson and blow it up. The escorting hunters of this strider will run past you with little combat and head for the supply depot near