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

Maybe I should create more creatures for the lizards?

I don't know... I think it wouldn't look very good. What about decorations? Can you get them from Heroes 6 and put them in Heroes 5?

Added 3 minutes later

Guys, can you tell me what the class ability and units will be instead of the Dungeon faction?

All racial abilities remain the same, just with different icons and names. The exception is the lizards; now, to gain "Blood Fury" (it will be called something else in the mod), they must defend themselves instead of attacking.