In this post i'm going to talk about what my basic rules are against xenomorphs. The marines as we know them have some equipment that anyone could use and could easily use. The tactics i think would be helpful are basic and effective, number 1: use cqb weapons and trip mines for defense at all times. Number 2: never use long range weapons in alien areas (since they are likely in rooms, hallways, tunnles, or caves). Number 3: use long lasting durable weapons with either an underslung shotgun or grenade launcher unless handgun or flamethrower. Number 4: be in squads of 5 at least with tactical knowledge of the area and if there is no knowledge of the area then find an area with communication abillities and fortify area. Number 5: Keep sentry guns with the squad and use as defensive unit only. Now if you have any questions please comment and while against aliens use common sense.