Turok

For this achievement I recommend you use a Sniper Rifle and pick off your enemies from a distance, take your time to ensure that you hit their head and once you get ten in a row the achievement will unlock. A good place to unlock this achievement is just before the "Spider Tank" comes out, when Slade calls for help and you run from the wreckage camp up to help him, stay outside the opening in the rocks and just zoom in on the enemies as they swarm. As long as you do not run in far enough to trigger the "cutscene" with the soldier with the RPG, the enemies should keep spawning.