When you begin the game you must initially go to monster areas to get enough gems to upgrade your weapon

Beginning of the game

monster area one

upgraded weapons allow for player to access harder areas of the game

Monster area 2

additional room where you can fight ditto and access a chest for gems and health

this is one of the most difficult rooms in the game.  After you defeat all the large and small pokemon you can gain a huge amount of gems and regain health.

Then you can access a side room from the first monster area to fight a supersized ditto that spawns smaller ditto when hit.  If you defeat him you can go through the door which ultimately beats the game.

Shows what the end scene says