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For a first attempt, it's very good. Except for the balance. I had it in my chest, which means I played it sometime. I specifically found the author here and want to suggest (if he wants) a couple of tweaks. The balance is off at the beginning. The Gatekeeper with manticores can be defeated with the loss of only two units (gremlin + golem) – then, in the valley, the difficulty suddenly jumps up several notches because you try to avoid losses, but in the middle of the game, you realize that you don't want to take dwarves and creatures. The valley with the phoenix is the only interesting place in terms of battles. After meeting the dwarves, almost all battles can be won on auto-battle. The final is completely messed up. The main boss is weak. The rakshasas as a bonus are just a mockery of the necromancer, who already has no chance.
The quest is understandable why it's like that (it's the first map, after all). I would reduce the number of dwarves (+ban diplomacy) and strengthen the necromancer and the guards in the lands of the dwarves and mages, forcing the dwarves to cast walls instead of shooting. Something like that.
P.S. spoiler for myself (there's a mine for sorting).
P.P.S. the summon spell is completely useless (there are spells).