You earn a stamp at 200 points on each difficulty. You can see more details about the game in its how to play section, which is on the difficulty select menu. The data tab goes into a lot of detail about any specifics!
I see and one more thing , eventhough i manage the easy mode but in case if its too difficult could i have a save file with the secret unlocked or maybe an unlimited lives cheat until i got enough points to unlock a stamp?
