Game assets and environment looked good, but it was unclear how to attack. I think the units started attacking on their own, but it was hard to tell as only one unit would attack at a time even though they were all surrounding the enemy.
The two separate controllers seems like it could be fun for two people, but it was hard to get a handle on the controls as a single player.
With more of what you were planning I could see this being fun, but I would seriously consider if both the necromancer and the deathknight should always be in there. Perhaps have just necro for 1 player and is you select 2 player from the main menu it enables the deathknight. Just a thought.