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

UPDATE
FIXES - FIXES!!!!!

I managed to play a game before the fixes, and I didn't notice any critical bugs, except for that minor bug with the Archon's scythe, which they have already fixed, and the black space under the Knight when he dies.

Gameplay-wise, the Swamp Knights and the Risen Warriors are overpowered, without a doubt. Orson will dominate in the early stages of the map, especially in battles with neutrals.

Added 11 minutes later
I'll add: I spent most of the Town Economy on Warriors and Sisters (because of sieges), and I gathered a decent number of them. With the fix, as I understand it, this strategy will no longer work, and all the Town Economy goes only to skeletons.
Regarding Naadir's Flies, I didn't feel a significant gameplay difference, although I admit that sometimes their size saved them from larger units. It is quite possible that I did not fully appreciate this approach, as I focused on the Risen Warriors.
The Risen Warriors and their upgrades are nothing more than the quintessence of necromancy!