This game has unused code.
Unlike all of the other console Doom games, which are just ports of the PC versions, Doom 64 has all-new content and was developed specifically for the Nintendo 64. While it loses a couple of the monsters from Doom II due to limited cart space, it features higher resolution resources, some nifty colored lighting effects, and a form of scripting which allows level designers to create far more interesting setups than the original engine ever did.
There's a debug mode here; I'm not sure how it's accessed and IDK enough to find all the code IDA won't disassemble
Enter the password ?TJL BDFW BFGV JVVB then pause during gameplay to access a features menu, which contains a level select, invulnerability, health, and weapon toggles, and an option to view the whole map.
|US 1.0||8005A7D3 0001|
|US 1.1||8005A883 0001|
In an interview with the website Doom Depot, level designer Tim Heydelaar claimed that there was an undiscovered secret in Level 20: Breakdown. While this secret has seemingly been removed from the final game, remnants of it still exist – in particular, several one-sided linedefs with no action and method of activation are flagged as hidden. The hidden flag is used for obscuring sector height differences and interactive lines in the game's automap, making them appear as normal one-sided lines, and its use is pointless in the case of these lines.
While these flagged lines may simply be a mistake, several are in the room with the red key and one is in the secret room with the BFG9000, locations Tim mentions in the interview. In addition to the flagged lines, macro 17 is intended to activate on level start, but lacks the flag required to do so. Macro 23 lowers the floor of a sector with tag 27, but no sector with this tag exists. There are also references to macros 24 and 25, which do not exist.
The default brightness setting has been increased in the European and Japanese releases.
The blood spatter sprites have been recolored green in the Japanese version. The blood on the monster death sprites and various gore decorations is still red, however.
Two versions (1.0 and 1.1) of the US ROM exist. While the actual functional difference between them is unknown, 1.1 contains an unused copy of the European version's copyright screen (under the lump name "PLLEGAL"), but does not carry over the increased default brightness from the actual European ROM.
Leftover Debug Strings
Stored in the ROM in the list of strings used for the various menus are strings:
DEBUG TEXTURE TEST WALL BLOCKING
LOCK MONSTERS SCREENSHOT
MACRO PEEK MUSIC TEST WARP TO FUN
(They are separated by various used strings.)
These strings are all that is left of debug functionality that was to be part of the Features menu. You can re-activate these in the Features menu with the below GameShark code, however they do not have any functionality left.
Unused Features Menu Options Set 1:
|USA|| 8005AB67 001A|
Unused Features Menu Options Set 2:
|USA|| 8005AB67 0026|
Debug Crash Text
If the game ever crashed in a certain way, these messages would appear on screen and lock the game.
An odd texture that, unsurprisingly, doesn't appear during regular play. It automatically appears on walls that lack textures. Very rarely seen, it can be found when the player "breaks" the room-over-room effect, stumbling into a room inescapable without cheating. It's titled with a question mark in the game's internal WAD.
Two sounds related to the Zombieman and Shotgun Guy enemies that go unused, because the game has a limit of at most 2 sets of sounds for enemies sighting the player and their death animation.
Two sounds related to the Revenant enemy from Doom 2 that were most likely carried over from the PlayStation version of Doom, which Doom 64 is based on. One being the "action" sound Revenants chasing the player make, and the "punching" sound they make when their melee attack connects.
According to Tim Heydelaar, the monsters from Doom 2 that didn't make it into the game were cut due to storage constraints. Apparently, there were intentions to include at least the Revenant, since Randy Estrella has expressed his favoritism towards the enemy. Other sounds related to the Revenant are found whithin the ROM, but are given different names and uses. The swinging fist sound (originally DSSKESWG, renamed SNDDART in Doom 64) is reused as part of the dart traps found in some of the maps, and the Revenant fireball sound (DSSKEATK, named SNDTRACR in Doom 64) is used by the homing fireball traps, as well as Mother Demon's homing fireball attack.
|The Doom series|
|DOS||Doom (1993) (Prototypes) • Doom II: Hell on Earth • Final Doom|
|Windows||Doom (1993) (Prototypes) • Doom 3 (Prototypes) • Doom (2016)|
|Mac OS Classic||Doom (1993) (Prototypes) • Doom II: Hell on Earth • Final Doom|
|Mac OS X||Doom 3 (Prototypes)|
|Linux||Doom (1993) (Prototypes)|
|PlayStation||Doom • Final Doom|
|Nintendo 64||Doom 64|
|Game Boy Advance||Doom • Doom II: Hell on Earth|
|J2ME||Doom RPG • Doom II RPG|
|Xbox 360||Doom II: Hell on Earth|
|PlayStation 3||Doom II: Hell on Earth • Final Doom|