1. Difficulty adjustment - Bikini, Tunnel and Cave campaign Double the HP of Characters who need protecting such as researcher at Bikini - Normal vs Veteran If you choose normal mode, you will play it without the emergence of boss. Only veteran mode provides boss. 2. Gun play When you use both hand play guns such as minigun, now you can tilt them in line with your hand pulling the trigger just like in real world. 3. Boss Add new boss to tunnel campaign.