I've got a 440FX board with dual PPros at 233, 128MB RAM and a Voodoo Banshee running NT4.0 SP6 and it's... fun to mess around with. You can definitely run some games, provided they don't require Direct3D and/or don't specifically rely on libraries from DirectX5 and up. So that kinda limits things, but you can play some good 'ol Blizzard games, Quake 1 - 3, Unreal and Unreal Tournament, so already you're nicely covered there. At some point, when I have more space, I want to attempt to set that system up as an Unreal or UT dedicated server. I think it's been on my mind ever since I first read that Unreal technical supplement, they were basically recommending Pentium Pro and NT4 for that job!

I have noticed however that sometimes I get crackling sound on some games and I'm not sure what the deal is. I've tried different, mostly Creative soundcards and it is an issue I've had pop up on an earlier, single CPU 440FX board.

Have you tried it on any systems of yours?

Windows NT 4.0 is my favorite operating system of all time. There's enough OpenGL (and Glide) games to run to justify its existence in one's retro collection. It's stable and indeed, light. Looking back...when I first used NT 4.0, it was clunky slow, and a tremendous pain to get working properly; I had no idea of no "Plug and Play" support. ...Sniff... those were the days.

But my best memory was working on mandatory profiles, setting my desktop just the way I like it, logging off and then back in, and then.. POOF.... everything gone... I was angry that day, heh.

G-Nome, 7th Legion, Rollercoaster Tycoon, Tiberian Sun, and Dark Forces II all run well with the hacked DX5 patch. Flight Simulator 98 warns of limited functionality but also runs fine.

Anything OpenGL will run. As well as the Quakes and Half-Life you have things like RTCW and McGee's Alice which run nice on NT.

Take care with retail copies of StarCraft. The 2007 release says on the back cover that it it supports NT and the classic Mac OS, but in fact doesn't. The installers refuse to run. I had to get a copy of the 2001 release to install the game on these systems.

I've a soft spot for NT4. I've a Dual Slot 1 Compaq Prolent 600 NT4 "retro" file server and a Dual S604 Dell Precision 650 running the full backoffice suite just to mess around with.
But for gaming I just find it too limiting...

Hi there! I was running some games on NT 4 in the mid-late 2000s.
Cave Story, Undertale, HoldOver, SRB 2 v1. 08 (OpenGL mode)..

You may find this thread interesting, too! ^^
Video Games running with only GDI32.DLL

Edit: Also useful, maybe.
Emulation on Windows NT 4.0
Emulation on MS Windows 3.1x ?
KEGA Fusion 3.64 - Genesis-MegeDrive /32x/Sega CD - confirmed working in Windows 98