Blog author here, in 2020 I released a DOS game built completely in my own Forth system. Fully open source and hackable. https://spindleyq.itch.io/neut-tower
The coolest application of the Forth philosophy in that project was actually building tools that integrate directly with the engine, imo. I built a map and tile editor directly into the game for quickly iterating on art and level design, and at one point even added a slide presentation engine for giving talks with that had live demos integrated directly into slides. The eureka moment was when I added map editing and realized that I didn't need to write a fancy GUI just for saving and loading maps, because I had a live Forth console running over the serial port. As soon as I'd written the save/load routines they were immediately, directly usable.
Death Road to Canada is another game I'm aware of that is written in Forth, for more modern platforms.
There was a bit of discussion over on Reddit of a game called "Cosmic Conquest", printed in an edition of Byte magazine, that is supposed to be the first space RTS. That was entirely written in Forth on the Apple II.
A few of us managed to resurrect the code, and I've managed to get it more-or-less working as intended. Once I get time I'll tidy up the bits I wrote so they're fit to show in public.
