Wrapped in flesh, engraved with a pentagram, and fully upgradeable via 3 special artifacts, the Unmaker was undoubtedly the most different weapon designed from the Original Doom Bible specifications for Doom 64.
The weapon is described as a Laser Rifle at which upon pickup the HUD reads "What the &%@$ is this?!" possibly emanating the weapon was an experimental weapon developed either by Doom's Demonic forces or a prototype weapon left over after the Final Doom events. The true nature of this is undisclosed.
Found as early as Secret Level 29: Outpost Omega or Level 12: The Alter of Pain depending on if you find the Secret Levels, the weapon is initially as powerful as a normal Plasma Rifle, though slower to fire. The design of the blast is a searing hot beam similar to the size of a round from the Pistol. As such the Unmaker can be useful in fighting from behind barriers, through gates, or other places where often you are a bit safer (The Cyberdemon is Level 16 watch Your Step can be fought from behind the other side of the exit gate with this weapon from complete safety). Upon upgrade via the 3 hidden Artifacts (a collection of Red, Blue, and Violet Pentagram symbols) the power levels rise dramatically doubling each time a new artifact is found. Initially the power level is rated at 1.5x or 1.5 times the power of a single Pistol Shot equal to a Plasma Rifle round, and grows to 3.0, 6.0, and 12.0 in power. The 6.0 and 12.0 power ranges also add multiple blasts of laser beams which in effect add to the damage calculation. 6.0 adds a 2nd beam while the 12.0 adds a third beam. This effectively increases combined damage from 6.0 to 12.0 and 12.0 to 36.0 pending the collection of shots strike the target at the same time. Each additional beam also consumes an extra round of ammo also.
Though several publications have rated the weapon more powerful than the infamous BFG9000 the damage calculation would prove otherwise.
The Artifacts also serve as a set of Keys in Level 28: The Absolution to close the gates spawning the monsters.
In the Doom Source Port of the Doom64 TC, a spin off of the Doomsday or DENG source port, the Unmaker is included but without the Beam effect but instead a Red Plasma shot making fighting from behind barriers impossible. In the add-on Outcast package two new Artifacts power up the Unmaker even farther.
Hell time: A powerup that adds a slow-motion effect upon the environment and monsters.
Levitator: A power up that creates Small blocks or platforms for the player to utilize.