Mechanic details

• The player, the monsters, and the merchants act as three separate parties.

• The player needs to beat up monsters for exp points and resources to sell and to buy potions from merchants to continue to fight.

• The monsters need healing and reviving to survive (also bought from merchants) and the merchants need potion ingredients from the player and the monsters to make potions to sell.

• These potions are only able to be processed in such bulk by merchants thus their potions would be cheaper than making them yourself.

• Only the monsters can farm ingredients in bulk.

• Only the player is or has to be overly aggressive (in bulk).

• Monsters can farm and produce "Level up candies" that do the work of exp. they are eaten right away after they are made and are never stockpiled or held for fear of the player and merchants who want to sell to the player.

• The monsters will defend themselves. Reviving is very expensive.

• The merchants can be found either with a concerned expression or a grinning expression based on how much profit they are making compared to their morale standing.

• The economies of each monster town and merchant city are distinct but interconnected.

• Magic Swords are worth a lot.

So what I need to know is what concerns would there be to design a game around this mechanic and/or design this mechanic around a developing game. which would fare better? Is game balance an issue here? (how strong the monsters get or how quickly they die off based on the player's input into the system), Or is game balance solely in the hands of the player? (he decides if he overkills monsters or get underleveled.)

What do I need to think about to make sure it isn't too easy or too hard to swing the amount/strength of monsters compared to the player and the amount of profit the merchants get vs the player. Would indicating how out of whack things are getting in game help with this?