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

No, Necropolis just has a lot of cool, inspiring units.

Actually, I like Dwarves the most.

Necropolis has a problem with its conceptual part – they have too many unit variations; I think this is related to the fact that undead are usually just cannon fodder.

That is, the classics are: skeleton, zombie, ghost, vampire, lich – this is a standard set.

But skeletons can be divided into infantry and archers (at different levels); in the case of the resurrected Roman legion, this looks appropriate.

You can use mummies; there are various ghouls, resurrected animals; ghosts can be in cloaks, they can be transparent, they can look like elementals made of dust; vampires are also divided into several types; there is a demilich; I think you can list them for a long time.

For the most part, Necropolis includes units inspired by something; for example, I really like the Dark Messiah (infantry in armor from the Dark Messiah), then one of the infantry in the Guardian helmet (this is undead inspired by Markel); skeleton archers are an old idea of Necro-Romans, that is, there is infantry and a separate archer unit.

Of course, there is undead imitating the sixth Heroes game (I love the sixth Heroes), then there are ghouls – this is a development of the old idea of skull demons, it was initially inspired by enemies from the Overlord game, and then I was inspired by wendigos.

And the most unusual unit of the whole bunch is the fly – I wasn't inspired by anything; I took the effects from the water elemental and saw quickly twitching streams of water, and that was it – a spark, a storm, madness; I attached wings to the streams.

It's more pleasant to work with inspiration; for example, Chaos Dwarves turned out worse because I decided to make a Dwarven GHOST – T1, T2, T3, and T4 have the same armor, only the black possessed one has heavy armor; this turned into a routine. Ifrits and Titans became a breath of fresh air.

Added 4 minutes ago
The only thing I don't like is the concept of Necropolis as a whole – there is one guy and his puppets, THAT'S ALL... so I have to come up with some kind of undead factions that are fighting for power.