Hi all,
Long time lurker who thought this might be a good place to share what I've discovered looking through the recent uploads of Midway arcade game source code.
If you weren't aware already, someone uploaded a load of source code and other assets from '90s Midway coin-ops in the past week. Looking through it there are lots of ROMsets not in MAME as well as generally interesting information on the development and history of these games. Feel free to add anything you might have found in this thread.

It includes things like a previously unknown and unreleased game called RoadKill (aka Derby Race as it seems to be called in the source as a placeholder name) that at a glance seems to be something like Atari's Badlands.

I've only looked at a few games in detail so far, but the below are my findings:

NBA Hangtime

Note the repository seems to include data for NBA Hangtime AND NBA Maximum Hangtime mixed together. Max Hangtime data seems to be denoted by an X before filenames.

Compiled ROMs Present - Yes
Version History - Yes, see nba-hangtime/SRC/CHANGES.DOC See also nba-hangtime/SRC/REVUP.DOC
Source latest version - appears to be 1.3 from nba-hangtime/SRC/CHANGES.DOC
Previous version source - Yes, backups of most old versions seem to have been included

Compiled ROMs
As far as I can see, only the program ROMs have been included for this game, unlike some of the other games below that have everything.

Program ROMs
NBA Hangtime
L1.1 - 04/16/96 - Already present in MAME and matches existing ROMs
M1.1 - 04/16/96 - New, not in MAME
L1.2 - 08/29/96 - New, not in MAME
M1.2 - 08/29/96 - New, not in MAME
M1.3 - 10/10/96 - New, not in MAME
L1.3 - 10/10/96 - New, not in MAME

NBA Maximum Hangtime
L0.9 - 10/30/96 - New, not in MAME
L1.0 - 11/08/96 - Already present in MAME and matches existing ROMs
M1.0 - 11/08/96 - New, not in MAME

(Note version 1.03 of Max Hangtime already included in MAME is NOT present here)

Interesting Things

nba-hangtime/SRC/COMBOS.DOC - all combination codes to unlock the various cheats/fun modes in the game
nba-hangtime/SRC/TODO.DOC - Todo list of new features and bugs to fix. There are also older versions of this file in the old backups that document how the game progressed during development


Compiled ROMs Present - Yes
Version History - Yes, see narc/NARC/NARCREVS.DOC
Source latest version - appears to be 7.00 from NARCHELP.ASM
Previous version source - No

Compiled ROMs

Program ROMs
Rev 6.00 - New, not in MAME
Rev 7.00 - Already present in MAME and matches existing ROMs

Graphics ROMs are located in narc/IMG/IROM/ These are identical to the ones already in MAME
Sound ROMs are located in narc/SOUND/ NONE of these match MAME:

NYAM6.PP rev2_narc_sound_rom_u5.u5 99.984741%
NDIG6.PP rev2_narc_sound_rom_u38.u38 99.693298%
NYAM4.PP rev2_narc_sound_rom_u4.u4 61.810303%
NDIG4.PP rev2_narc_sound_rom_u37.u37 56.472778%
NDIG2.PP rev2_narc_sound_rom_u36.u36 54.211426%
NDIG0.PP rev2_narc_sound_rom_u35.u35 50.057983%

Interesting things

narc/NARC/DUMP.DOC - this is a document listing observations from a location test (how far players got, bugs, etc). Claims to be for version 1.91, which does not appear in the version history document
narc/NARC/NARC.DOC - How to build Narc in interlaced display mode
narc/NARC/NARCCART.DOC - George N Petro's comments on the NES home port of Narc
narc/NARC/NARCREVS.DOC - Version history with amusing comments on both what was fixed between versions but also complaining about managemment decisions
narc/NARC/NARCSTUF.DOC - Todo list/idea list from unknown period of development
narc/SOUND/WAVMUSIC.DOC - List of songs used in the game with their names


Compiled ROMs Present - Yes
Version History - No
Source latest version - appears to be LA5 from TROGMENU.ASM
Previous version source - No

Compiled ROMs

Program ROMs
LA3 - 02/10/91 - New, not in MAME (Note this is DIFFERENT to the build of LA3 already in MAME, which is dated 02/14/91. Both ROMs in this new set are different)
LA5 - 03/29/91 - Already present in MAME and matches existing ROMs
PA5-PAC 08/28/90 - New, not in MAME (these are the files TROGFE.0 and TROGFE.1 in the main directory. Presumably this is also the first "Pac-Man" build of the game created)

Graphics ROMs for Trog can be found in trog/IMG/IROM/ These are identical to the ones in MAME APART from two that are very slightly different:
TROG428.0 trog_ii_u-113_la-1.u113 99.566650%
TROG428.1 trog_ii_u-97_la-1.u97 99.520111%

Sound ROMs for the game are in trog/SOUND/ and are identical to the ones in MAME

Appears to also have two versions of Trog for NES, but quick testing of these didn't seem to work in FCEUX

Interesting Things

trog/TROGPROJ.DOC - Design brief for the project. This is for the original version of the game (i.e. non "PAC"). At this stage the idea was each player was a different kind of dinosaur rather than just a recolour of the same one as in the what was created for the game
trog/ROMS.DOC - List of constituent ROMs of game version PA3-PAC dated 8/15/90. This version is not in MAME and seemingly not included in the repository unfortunately
trog/TROGIDEA.DOC - List of ideas to add to the game, including a "Rally X" style bonus level
trog/READ.ME - Confirms LA5 is final version

I'll look at the other games later.