BOBs: The others who you will encounter in the game are known as BOBs (which stands for "Born On Board"). These characters are other inhabitants of the ship, and generally ignore the player. In Durandal and Infinity, these characters carry weapons and will fire at the enemy along with you. If you attack the BOBs, they will return fire, seeing you as a traitor. Some of the BOBs have actually been assimilated by the Pfhor, and are basically walking bombs. Upon seeing you, they will run towards you shouting things like "Thank God it's you!" or "I'm out of ammo!" or the infamous "Frog blast the vent core!" This last phrase is of particular interest, and has become synonymous with the Marathon series. The following quote from the man who did the voice work for the BOBs, Doug Zartman, talks about where the line came from:
The idea was that some of the assimilated Bobs become insane from their conversion and run around yelling nonsense. Alex said to me 'say something random,' and that phrase tumbled from my lips. Totally spontaneous. While I could have sat down and thought up something more random than that, it worked out well, since it sounds close enough to a real sentence that it kept people guessing and generated some fascinating (and totally wrong) discussion about what the phrase was and its meaning. One popular theory was 'God bless the Marine Corps!', which was a fair guess, but still wrong.
When close enough, the assimilated BOB will explode, inflicting damage on the player and surrounding BOBs. This is particularly annoying in levels were you have to save a certain number of BOBs. Another way to tell assimilated BOBs from actual BOBs is their yellow blood.
You are given a number of weapons to use in dispatching the various alien baddies. The fall-back is always your fists, a single fist in the first Marathon, and two fists in Durandal and Infinity. Close range, and no ammo needed.
The pistol is a .45 caliber Magnum. The bullets do moderate damage, but the firing rate is slow, and there are only 8 bullets per magazine. The pistol is capable of firing in a vacuum.
The assault rifle is a much faster firing weapon, at 600 rounds per minute, with a 52-round magazine. The weapon also comes with a grenade option, firing 7-round magazines at a very slow rate. Neither of these weapons can be used in a vacuum.
The fusion pistol is an energy weapon. It is fed by batteries and can fire in a vacuum. There are two firing modes for the fusion pistol: standard and overload. Overload consists of charging the weapon before firing. If held too long, the weapon may discharge explosively, killing the player. The weapon discharges immediately if fired underwater, causing the player and anything touching the player to take damage.
The rocket launcher, or "SPNKR" is a shoulder-mounted launcher that fires two unguided rounds. The rockets have a 10 meter blast radius, and fly at over 110 meters per second.
The flamethrower uses a napalm pack that allows for seven seconds of continuous use. Obviously, the flamethrower cannot be used in a vacuum. Due to a quirk of the physics engine in the original Marathon, the flamethrower could be used as a jetpack in some low-gravity Pfhor missions.
The combat shotgun is a particularly powerful weapon. Its ammo, when discharged, does not stop when hitting an enemy, but continues through, damaging anything behind the enemy as well. It fires two 12-gauge rounds at once.