Alright, want to play this game I remember playing as a child, but i dont remember its name.
In the game you played as some kingdom, in the middle of a map you had a castle. You would defend it from monsters or some stuff, and you could send out heroes to kill the monsters, they would also level up from killing not sure if you were able to upgrade them or not. That's all I remember, hope it's enough for you to find it for me :3
Also, they might have not been heroes but randomly wandering units you could create.