RTF is a global modification that replaces all towns in the game.

I'll write here, don't want to go to Discord...

Cool, a Yeti! I didn't even know about that... and how do you tell if it's been removed? Like, is there just a model in the game files and that's it?

Well, something like that... besides the Yeti, there's a lizard archer, and a Naga - she's even animated, but all her animations are in one huge file... plus, there are removed heroes (cavalry) and some kind of demon hero or demon creature! And there are also insider files with several models in Alias Maya format - they are animated...