A classic PC game following this pattern is Stunts 4D Sports Driving. It consists of common game code, a CGA/Hercules specific part, an EGA part and an MCGA part, and links the common code and the graphics mode specific part when you start the game, using patches to the common code to fix up the addresses.

Hmm, I just has a quick look. Here's what I have installed in that category. This is just from memory, so I might have missed a few.

Expendable - launcher runs separate binary
Midnight GT - launcher runs separate binary
Neverwinter Nights - launcher runs separate binary
NFL Blitz - config tool built in to binary
Powerdrome (2005) - built in launcher
Rollcage Stage II - launcher runs subfolder binary
Sports Car GT - built in launcher
Viper Racing - exe runs subfolder bin file

Flashback wrote on 2022-09-29, 19:30:

Hmm, I just has a quick look. Here's what I have installed in that category. This is just from memory, so I might have missed a […]
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Hmm, I just has a quick look. Here's what I have installed in that category. This is just from memory, so I might have missed a few.

Expendable - launcher runs separate binary
Midnight GT - launcher runs separate binary
Neverwinter Nights - launcher runs separate binary
NFL Blitz - config tool built in to binary
Powerdrome (2005) - built in launcher
Rollcage Stage II - launcher runs subfolder binary
Sports Car GT - built in launcher
Viper Racing - exe runs subfolder bin file

I think Resident Evil 1 also has such a case where it runs from a "biovfwus.bin"

Sega's Outrun has the executables disguised as data files. This is to avoid players bypassing the copy protection routine, which is in the launcher. Once you know which files are which you can just rename one of them (CGA/EGA/Tandy) to OUTRUN.EXE and launch it directly.

I suppose the idea is to identify games where the program code (as opposed to just data) exist in some other file, outside the primary executable?

In my DOS gaming archive I can spot the following:

• Alien Carnage - main program (CARNAGE.EXE) is <10KB, so obviously the code is somewhere else. There are a bunch of HARRY*.-0 files that have the "MZ" header, so I suppose it is split between them somehow, but renaming them to .EXE and running them directly does not work - they probably need some arguments or in-memory modification.
• Chasm: The Rift - CHASM.EXE launches PS10.EXE, after setting up the environment somehow. Launching PS10.EXE directly tells you to run CHASM.EXE instead.
• Cool Spot - main program (SPOT.EXE) is ~1K. There are two files - ZX.BUM and MUS.BUM which appear to be executables. Launching ZX.BUM directly starts the main game, but without sound. Launching MUS.BUM locks up my DOSBOX, so it must be somehow responsible for initializing the sound, but needs adjustments.
• Lemmings 2: The Tribes - Main EXE (L2.EXE) is only 6720 bytes. I cannot figure out exactly where the code is. DOSBox debugger shows a bunch of calls to open the various RKO/RKB files in the game directory - it is probably split between the bunch of them somehow.
• Lotus: The Ultimate Challenge - LOTUS.EXE is <5K, most of the code is in LOTUS.DAT.
• Paganitzu - PAGA?.EXE (where ? is 1,2,3 depending on the episode) is a front-end to configure graphics, sound and control options every time you start it (it also tells you about the command-line arguments you can use to bypass the prompt screens). After that, it launches PAGA?.001, which is the main menu. That, in turn, launches PAGA?.002, which starts the game. Renaming the .001 and .002 files to EXE allows them to be launched directly.
• Volfied - VOLFIED.EXE is ~3.5K. It loads code from CGA.PRG, EGA.PRG, TGA.PRG or VGA.PRG, depending on autodetected video capabilities, or commandline arguments. The .PRG files are not well-formed executables, and cannot be launched by themselves. Note: I have a cracked version, not sure whether anything is different in the original.
• Zool 2 - ZOOL2.EXE is ~1.5K, most of the code is in ZOOL2.DAT.

Epic Megagames seemed to have a knack for convoluted system of front-ends via batch files launching other batchfiles and executables:

• Heartlight - has a main batchfile (HEART.BAT) launching other batch files and executables as front-ends. The main program is in HL.DAT, and it can be run directly if renamed to .EXE, skipping all the front-ends.
• Jazz Jackrabbit (CD version) - The main program is FILE0001.EXE. The front-end (JAZZ.EXE) checks whether sound settings exist, and if not, launches SETUP.EXE first. This front-end was removed from the "Holiday Hare" 94/95 editions, where JAZZ.EXE is the main program.
• Jill of the Jungle - an even more crazy system of batch files to launch the episode selection / order instruction front-ends. Each episode is its own EXE file, though, and can be run directly.
• One Must Fall 2097 - Like in Jazz CD version, the main program is FILE0001.EXE. The front-end (OMF.EXE) presents a menu that allows choosing between the main game, multiplayer games, and setup and order info programs, but most of these can be run directly, bypassing the front-end.
• Xargon - same as Jill of the Jungle.

I'm not including games which are designed to be launched from a simple batch file that is just calling the main executable with some parameters.

dr_st wrote on 2022-09-30, 17:03:

Lemmings 2: The Tribes - Main EXE (L2.EXE) is only 6720 bytes. I cannot figure out exactly where the code is. DOSBox debugger shows a bunch of calls to open the various RKO/RKB files in the game directory - it is probably split between the bunch of them somehow.

The RKO files are kind of object files, which are linked (really resolving imports/exports) at start-up time of Lemmings 2.