Chainsaw

The chainsaw serves a fundamentally different tactical purpose from the guns in the marine’s arsenal: it demands that the player close the distance, accept the risk of proximity, and trade bullets for blood — essentially, ammo conservation at the cost of personal safety.

Origins and development

The chainsaw’s visual identity has a surprisingly mundane origin. The in-game graphics were derived from scans of a real chainsaw — a McCulloch Eager Beaver — borrowed by id Software’s Tom Hall from his then-girlfriend and photographed; the scans were then used to create the weapon graphics. The weapon itself was a somewhat late arrival to the game’s arsenal; it does not appear in the Doom Bible, the early design document that outlined much of the game’s content. A crude pickup sprite is visible as far back as Doom v0.3, while the first-person and standard pickup sprites first materialized in Doom v0.4 alpha, though the weapon did not become fully functional until the press release beta.

The decision to include a chainsaw — alongside the shotgun — drew its inspiration from the 1987 comedy-horror film Evil Dead II. In that film, protagonist Ash Williams loses his right hand to a demonic infection and fashions a chainsaw attachment to his arm stump, using it against the undead.

Mechanics and performance

Mechanically, the chainsaw fires at 525 attacks per minute — one hit every 4 tics — making it roughly four times as fast as the bare fist. Each individual tooth impact uses the A_Saw() damage function, which calculates (x + 1) * 2 damage where x is a random integer between 0 and 9, yielding a per-hit range of 2 to 20 points. Averaged over time, this works out to roughly 96.25 damage points each second against unobstructed targets.

Notably, the chainsaw shares its total animation frame count and timing with the chaingun, giving both weapons an identical rate of fire. However, because the mean damage of a single chainsaw tooth exceeds that of a single chaingun bullet, the chainsaw edges ahead in raw damage-per-second. The chaingun’s A_FireCGun() function calls P_GunShot(), which produces x * 5 damage, with x drawn randomly from the range 1 to 3, a slightly lower average than the saw’s formula.

The weapon’s effective reach is 64 map units, the same as the fist’s 64-unit range. In the original Doom and Doom II, the chainsaw does not consume ammo; its supply is effectively infinite, making it a pure conservation tool in extended engagements. Later versions use fuel instead: the chainsaw in Doom (2016) and Doom Eternal requires fuel to power the weapon.

Tactical considerations

• The chainsaw excels against enemies with a high pain chance. Demons and spectres are its primary targets: the player can typically dispatch both without sustaining damage, provided the approach is managed carefully. Against packs of these monsters, veteran players back into a corner narrow enough — under 107 degrees of width — that only a single demon can attack at a time, chainsawing each in sequence.
• The weapon is also reasonably effective against cacodemons, lost souls, pain elementals, and imps. Against revenants, a viable but demanding technique involves continuously backing off to maintain a distance outside the revenant’s melee range but inside its rocket minimum — a gap that requires precise movement.
• Against hell knights and other demons with powerful attacks and low pain chance, the chainsaw becomes ineffective. Mancubi pose a different kind of risk: the monster may suddenly retaliate mid-attack, though this can be reduced by using several short bursts rather than staying in continuous contact.
• A significant caveat: in vanilla Doom, the chainsaw is unreliable against the arachnotron, mancubus, and spider mastermind because of the engine’s hitscan collision behavior; source ports that modify this behavior can restore reliable contact against these targets.
• On Nightmare! difficulty or when using the -fast parameter, the chainsaw also loses much of its advantage against demons and spectres, as those monsters’ melee attacks and pain recovery both operate at double speed.
• Holding the chainsaw does not alert nearby monsters in open areas — only actively firing it does. This gives players a subtle option: switching to the chainsaw for its continuous idle buzz, then deliberately “revving” it to draw enemies without expending ammunition on a ranged weapon.
• In vanilla Doom, once a player possesses a chainsaw, they cannot switch back to the fists unless they also carry a berserk pack. Most modern source ports remove this restriction, allowing the player to toggle between the two by pressing the weapon slot 1 key. In the PlayStation and Saturn ports and in Doom 64, the fist remains selectable after picking up the chainsaw, regardless of whether the player has berserk.
• In Doom Eternal, use the chainsaw when ammunition is running low to replenish your ammo supply. Chainsawing suitable enemies produces ammunition, making the weapon an important way to recover resources during combat.

Cheat access

Players can obtain the chainsaw via three cheat codes: idchoppers, idfa, and idkfa. The idchoppers code carries a notable bug: it is designed to also grant temporary invulnerability, but because the invulnerability timer is set to true (the boolean value 1) rather than a proper duration, the invulnerability expires after a single game tic — rendering it effectively useless.

The Doom 64 variant

Doom 64 features a substantially different version of the chainsaw. Visually, the saw carries two blades instead of one, and the letters “U.A.C.” are engraved on the weapon’s body. Mechanically, it is significantly more powerful: it attacks at 900 teeth per minute and uses the damage formula (x + 1) * 3 where x is a random value between 0 and 7, yielding a per-hit range of 3 to 24 points. Doom 64 runs at 30 tics per second rather than 35, and the weapon deals damage once every 2 tics (approximately 0.066 seconds), making this variant roughly double the damage output of the original.

Engine behavior and sound

Due to the Doom engine’s collision model, the chainsaw does not penetrate its victims. When a hit connects, the engine turns the player’s angle toward the target. If the target is more than 4.5 degrees away, the player’s view is swung to within approximately 4.3 degrees of the target in a single hit; only when the target is already within 4.5 degrees does the engine make a smaller nudge of up to 4.5 degrees. The engine also forces one tic of forward movement while zeroing the player’s turn input. The chainsaw is also unique among Doom’s weapons in not applying the usual knockback to its target. Together, the sudden angle adjustment, forced forward movement, and lack of knockback produce the familiar “locked on” feel when actively sawing an enemy.

The chainsaw’s sound design distinguishes between four states: the rev-up sound (DSSAWUP) when the weapon is selected, the idle sound (DSSAWIDL) while the weapon is held, the sound when you swing at the air and hit nothing (DSSAWFUL), and the hit confirmation sound (DSSAWHIT) when damage is dealt. The rev-up sound is normally truncated by the idle sound before it completes; it can be heard in full by pausing the game immediately after switching to the chainsaw. DSSAWUP also plays in full when a level starts with the chainsaw selected, and the attack sound can last longer than it normally does because it pauses while the weapon is attacking.

Legacy and lore

The chainsaw’s presence on Phobos is often deemed absurd — the moon has no plant life to justify a logging tool. Later entries in the series leaned into this: Doom 3 explains a chainsaw delivery to Mars as a shipping error (jackhammers were requested). Doom (2016) notes that the weapon was a forbidden black-market item at the UAC Mars Base and was subject to confiscation by UAC security before the facility was invaded by the forces of Hell. Doom Eternal later uses a fuel-limited chainsaw that refunds ammunition when enemies are killed with it, and the chainsaw is a mandatory pickup in Hell on Earth.