I have 5 factions (races):
Dendroids - their strength lies in tanking and healing
Savannah (Cats) - swift and strong
Undead - classic, what else can I say )
Elves - strong in magic
Swamp - let's say, they are like the Zerg in StarCraft
The light races are Cats and Elves, the dark ones are Undead and Swamp, and they are locked in a blood feud.
Dendroids are a neutral race.
Each race has its own standard level 1-7 creatures, but there are also extra units, which require certain special conditions to hire.
In total, the game has 5*(7+1)=40 different creatures.
I didn't implement magic like in the original Heroes 3; the hero has mana, but there is no spell book. Instead, the creatures themselves wield magic.
There are passive abilities that don't require mana. There are active (special) abilities, and depending on their power (whether the magic targets a single unit or is mass magic), they require more or less mana.
Another difference from classic Homm3 is that creatures have different sizes depending on their level, and this matters — it's hard for a level 7 creature to hit a level 1 creature.
Because of this, there is magic to "reduce target" or "enlarge target".
I've attached an archive with the game.
In the first dialog, press "yes" (though it doesn't matter, the world map isn't properly implemented yet), then "c" for castle, "g" if you don't want to manually recruit an army — to create a random battle. In battle, you can also press "c" to return to the castle placeholder to reorganize your army composition.