So I just bought the game, and upon starting it CTDs with an OpenGL error. Is there anyway to say switch to Software mode? Or any other way to circumvent the error?

Try running the game with the following parameters:

sin.exe +set vid_ref soft +menu_main

This activates software rendering. If it doesn't work right away, delete the generated config file and try again:

(installation path)\base\players\blade\config.cfg

In any case, it will be helpful if you post the OpenGL error.

I'm having trouble getting a screenshot but the error is:

"Failed to initialize OpenGL!"
" - Make sure display is set to 16 bits or more."

Ninja Edit: Also the config in the blade directory is totally missing. Probably due on the fact the game crashes right when I attempt to start it.

Welp, that's extra weird. Could you start the game with the parameters I gave you? You can create a shortcut to sin.exe and put them there.

Are you in Windows 10, and installed the game in an UAC protected folder? That is the recipe for disaster.

What are your PC specs? I'm particularly interested to know what videocard and drivers you are using. Also, what version of Windows? Anything you can post, will be helpful.

Okay so I slapped a shortcut onto my desktop with the ' +set vid_ref soft +menu_main ' - and it works.
New issue - I can't get the game into fullscreen. For now I've just altered the windows size to match my monitor and called it good but I'd like to see if I could circumvent that.

Do you still want my specs?
(also the game isn't in a UAC folder - double made sure of that first when it started doing this)

Edit: Okay not even a full minute into the first mission it hard locks and crashes.

If you are using GOG Galaxy, it would be practical if you can run "Verify / Repair". If not, reinstall the entire game.

Have you tried running Quake II in your PC? How does it run?
It's a related question, they run in the same engine. Other games like Kingpin and Soldier of Fortune also work for comparison.
What about other OpenGL games? Quake III Arena, Doom 3, Medal of Honor Allied Assault, etc.

For fullscreen, you can add the following to the list of parameters in your shortcut:
+set vid_fullscreen 1

Yes, I still want your specs. I have no idea what happens to you.

Yeah, I'll reinstall and or verify and see what happens.
Quake 2 runs pretty much flawless, as does Kingpin and SoF. Quake 2 only runs in software mode and refuses to boot in OpenGL. Kingpin plays without issue in either mode. SoF is the same.
Games like Quake 3, Doom 3 - run near flawless but Medal of Honor does not. At all.
This PC is a goddamn mystery man lol.

Specs are as follows:
Intel Core 2 Duo CPU E8400 @ 3.00ghz
12GBs of RAM
Intel Q45/Q43 Express Chipset
Windows 10

DX is updated to DX12 as well.

You should have started with that. This is no mystery, a Google search shows you are using a video chipset with no support at all for Windows 10
(https://www.bleepingcomputer.com/forums/t/587943/windows-10-upgrade-concern-about-graphics-intelr-q45q43/).
You are probably using a Microsoft driver, with support for OGL 1.4, but basic functionality.

I "believe" you are victim of the "OpenGL extensions problem", where if your video card supports a lot of them, and a game (i.e. Quake II) tries to print them, you get a buffer overflow. Newer drivers from Nvidia and AMD hide many extensions to some games, allowing them to run.

But there is a workaround. Download QeffectsGL:

https://github.com/crystice-softworks/QeffectsGL/releases

...and copy "opengl32.dll" and "QeffectsGL.ini" to the game's directory. Open the .ini file you just copied, and add the following section to it:

[sin.exe]
Hue=3
Saturation=0
Lightness=2
ExtensionLimit=4000
Anisotropy=0
Multisample=0
MultisampleHint=0
Bloom=0
SSAO=0
Emboss=0
DOF=0
Vignette=0

Save the file, delete the config file in the "blade" folder, and run the game with no parameters.

This is my guide thread on how I got OpenGL working when I first played the game back in 2018.
https://www.gog.com/forum/sin_gold/linux_wine_finally_made_opengl_work/page1

Scroll down for updated download links (the OpenGL DLL files and the REG Windows Registry file to be imported to the registry by running Regedit)

DOWNLOAD:
https://www.dropbox.com/sh/cy4b3dvu7k7clzp/AAA5Aju7NeDa6vZoVruhXDpJa?dl=0

For Linux/Wine users, you can access the registry by running wine cmd and then typing regedit [ENTER]

This is an older OpenGL DLL modified to still work on modern systems, I don't know about its history in particular but seems to be very close to the original OpenGL renderer included with the game, for the more original "raw" looks.
This OpenGL renderer also is capable of making the Wages of Sin flashlight be displayed correctly, as in Software renderer without all the CPU usage.

(no game files/assets included in these links, no piracy content, only CFG and INI files mostly)