-Concentrate on a working pathfinding for the opponents.
(not just turn and walk)
Else its hard to add this later into the game.

The opponents must also have a variance in action-states.
like enemies, who attack and run back some distance,
others forming a group and doing a rush-attack.

opponents running for cover when low on health.

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try to make a random-dungeon generator.
So that you have a collection of premade rooms with
standard connections.
The rooms are added up into a random maze later