Terran Marines aren't particularly quick and are easily killed by their powerful alien foes. Still, their Gauss Rifles are quick to fire, and while they aren't terribly powerful, the damage they inflict adds up quickly if the Marine isn't killed. Likewise, Marines can fire on flying targets just as well as they can deal with terrestrial ones, making them an effective air defense against all flying vessels. Gauss Rifles can and should be upgraded with U-238 shells, which significantly increase their effective range.

Researching Stim Packs lets your Marines temporarily boost their speed and rate of fire twofold at the cost of 10 hit points. Since Marines are easily eliminated one way or another, the ability to inflict double damage becomes an immense asset in many instances. Up to four Marines can also be stationed in immovable protective Bunkers for base defense or strategic placement. These Bunkers do not limit the Marines' ability to strike either ground or air targets, although they cannot use Stim Packs while in these closed quarters.

It cannot be stressed enough how important it is for Marines to attack in groups. Since they are inexpensive to train, the wise Terran commander will deploy legions of them against the enemy who might be overwhelmed by their devastating group fire. Though concentrated fire from a group of Marines will destroy anything and everything in relatively short order, they are best suited to quickly deal with small but key targets like the deadly Zerg Scourge or enemy worker units. Remember to use Marines' long reach and versatility to your advantage, and know that even as you develop more powerful alternatives to them on the battlefield, Marines remain very effective for base defense and frontline support throughout a battle.

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