Yes, i agree, the game is very easy.
Maybe fix and add some points to improve balance.
1 - Add a difficult levels changing the max HP and quantity of enemies.
2 - Add terrain fog feature.
3 - Increase of enemies run/walk velocity.
4 - Reduce a action distance for long range weapons.
5 - Increase price of equipment.
6 - Reduce gold and items dropped.

If i am not mistaken, items 3, 4, 5 and 6 are easier to implement, editing config files.
Items 1 and 2 need make changes in engine.