Colonial Marines are slow compared to their extraterrestrial foes, and they aren't particularly durable. But their vast array of military hardware makes them deadly: stay in a Colonial Marine's sights for even a moment and it's all over. You can kill most foes easily with the Colonial Marine's powerful weapons. The trick lies in spotting your enemies before they get too close. Aliens are so fast and numerous they'll overwhelm you if you aren't constantly vigilant. Predators, thanks to their cloaking ability, also can sneak up on you. It takes quick reflexes and constant alertness to succeed as a Colonial Marine.

Colonial Marines are hard-bitten human soldiers. Although not as fast or as durable as their enemies, their best weapons are potent enough to kill a foe almost instantly. Thus, the Marine must always strive to spot enemies from long range, either before or at the same time the enemy sees him, to buy a few seconds to discharge that powerful weaponry. Playing as the Marine, you can't be as wild and unpredictable as the Alien, But if your awareness and aim are both good, you stand a great chance of killing any enemy you encounter.