The Classic: Being Alone
This one takes the cake, as it’s both the most common and most preventable death.
Xenos thrive on isolated marines. Runners and lurkers will absolutely eviscerate you if they even think that they can get a few slashes off on you. If there are no fellow marines within your view range, then assume they won’t be able to help you in time if you get attacked.
Always walk in groups of at least two, depending on the time of day I’d say even 3-4, as during highpop hours the backline is so infested with Lurkers and Runners that they will easily destroy even a pair of marines.
Overextending
This one takes second place, as it’s really just a more advanced form of being alone. You’re still technically with your squad… until you’re not. Don’t be the guy that rushes into a resin door hoping to kill the retreating defender low on health. Any xeno standing behind that door will instantly rush to help defend their retreating comrade and completely obliterate you in the process. Even your fellow marines standing 7 tiles away won’t be able to help you as the warriors fling you around like a football.
Tunnel Vision
Tunnel vision is one of the sneakiest ways to get yourself killed. You get so focused on shooting a Xeno or finishing off a retreating enemy that you completely lose awareness of your surroundings. Meanwhile, Runners, Lurkers, or even a Warrior are circling around you, waiting for their moment to strike.
The classic example? You’re firing down a hallway, laser-focused on one Spitter, and don’t notice the Lurker coming up behind you until it’s too late.
Not Following Retreats
When the squad pulls back, you pull back too. Don’t be the guy standing their ground thinking you’re holding the line when everyone else has already fallen back to regroup. What usually happens? You get left alone, and Xenos pounce the moment they realize you’ve overcommitted.
Marines that don’t retreat when the squad does tend to die in embarrassing ways. If you hear a retreat called, stop what you’re doing and MOVE.
The Lone Hero
This is a death trap born of overconfidence. You think you can be the one to heroically kill the Xeno holding a choke point or save a pinned squadmate without backup. Except, you can’t. Xenos thrive on Marines who act alone, and being a “hero” just makes you a high-value target.
Even if you’re trying to rescue someone, call for help and wait for backup. Running in solo turns two dead Marines into three. There’s no glory in dying because you thought you could take on a Crusher by yourself.