Iron Demon
The Iron Demon is a mecha boss that was initially supposed to appear in Oni, making notable appearances in the 1999 trailer, but was cut during development as Bungie West raced to finish the game. According to 3D animator Steve Abeyta, "It was scrapped because it would take too long to create a custom AI, and gameplay for it. We had to cut a lot of stuff to get [Oni] shipped, and cutting that one sucked. […] Such a large character created AI pathfinding problems as well as issues with object interaction. They're not impossible to overcome, but we didn't have the time to tackle it."
The Iron Demon was stated as weighing 5 tons and standing 12 feet tall in this interview with Alex Seropian. If it had appeared as an enemy in-game, the player was going to get sufficiently heavy weaponry to fight it, per the same source. The striped cylinder on the Iron Demon's back, an ammo drum, was its weak point per Alex Okita. There was also an intention to allow the Iron Demon to be selectable in multiplayer mode per Hamilton Chu, though Kevin Armstrong doubted that it would be desirable to let players do that. No reports are known of the Iron Demon being seen in the multiplayer demos at various E3s and Macworld Expos.
In 2026, it was disclosed that the Iron Demon had been found in an alpha build of the game; see § Resurrection.
Official references
Promo screenshots
These are our best in-game looks at the original model:
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The appearance of the Iron Demon at the Regional State Building does not mean it was ever intended to be in that level. Per Hardy LeBel, RSB was one of the first levels created for the game and was used as a testbed during development.
Trailer
In the 1999 trailer, the Iron Demon can be seen in two scenes: one brief shot in Regional State and one extended walk sequence in unreleased MP arena The Pit (slowed down for careful inspection):
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In the second scene, a rocket launcher has been appended (perhaps somewhat hastily) to the right arm to show an alternate armament mode for the mecha.
Promo art
These are all the appearances of the Iron Demon in 2D art:
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Game assets
This section documents the assets relating to the Iron Demon that were shipped in the retail version of the game, but see § Resurrection to learn about the leaked alpha assets that came out later.
Unused sounds
The model geometry for the Iron Demon was not included in the released game data like some other "cut" content was, and we don't have its animations either (though Abeyta recalled only making "a walk cycle, firing anims, and possibly turning anims"). But some sounds for the Iron Demon were accidentally included in the final game as SNDDid_leg_[1-3].aif (possibly leg actuator sound effects, i.e. a leg being raised) and SNDDid_r_hit[1-4].aif (possibly intended for its footsteps if this name means "run hit", because Oni's existing footstep sounds are named like this: "SNDDkon_r_asph1.aif").
Unused script
Some versions of Oni accidentally included additional BSL scripts for levels that were cut during development. Perhaps the most intriguing of the cut levels was BGI, and the unfinished cutscene scripts for BGI include one scene with the following comments:
#create Iron Demon before player gets here ... #See Iron Demon ... #show Konoko getting ready for face-off ... #start battle
Apparently the plan was for the Iron Demon fight to occur in this level, however BGI HQ was cut while rushing to ship the game. (According to the design lead Hardy LeBel, it had not gotten very far along before it was removed.) The Iron Demon battle could have been moved to another level, but only if changes were made to the story and probably the voice acting, and it was likely too late to do that. In any case, as mentioned earlier, Bungie West did not have time to code the special-case AI behavior required for the Iron Demon to maneuver and fight within a 3D environment, and so the much-anticipated giant robot was left out of the final game.
Afterlife
In a story not revealed until May 2025, Robt McLees related on a live stream that he scattered parts of the Iron Demon in a Halo 2 multiplayer level called Foundation. (In fact it looks like he had to re-model the torso from scratch, and the other parts in the room seem to be a single part, cloned many times, which was not a component of the Demon.) The torso has been stamped with "TEST", and possibly with "ABANDON IN PLACE" like the other parts in the room, as a reference to its having been cut from Oni.
Resurrection
In January 2026, Iritscen announced that the original Iron Demon had been found in a leaked Windows alpha. The data included in the alpha build is the model geometry, textures and animations (the few that were made for it). There are two sounds listed for the Iron Demon, SND_IRONstep and SND_IRONsidestep, but they are not actually present in the data; this alpha build has no sounds due to being produced in the middle of a revamp of the sound code. (However the sounds might have been renamed at some point after this and thus could be the same as two of the SNDD files we have found in the retail data.)
At present, the resources connected to the Iron Demon have been extracted and turned into a proof-of-concept AE mod package (see our Discord server for the link), but it will need more work before it can be considered playable. In the meantime, the older fan recreation of the Iron Demon is available in the AE Installer (see below).
Fan content
3D models
Years before the original model leaked, there were three fan attempts to recreate the 3D model for the Iron Demon by inspecting the visual evidence we have from the pre-beta period:
- This model on TurboSquid by Ashley Davison. Never turned into a mod package.
- This model by Seventeen Seconds, used in Konoko Payne by Pierre but never made into a working character in Oni.
- This model by bobbysoon, based on the previous model. This one was turned into an AE mod package. The resulting Iron Demon character is used as an enemy in some mods which present battle arena scenarios.
