Initially the win criteria was within ±10% of the correct answer, but 15 minutes ago I changed it to ±20%. My rationale here is that the goal of the game is to get within the ballpark of the correct answer. And a guess of 80 billion when the correct answer is 100 billion seems quite good and indeed should probably win the game.

Thank you for making this.

I have an idea for a gameplay that I think I would enjoy more:

  - If the first guess is within a factor of sqrt(10), then you win.
  - If not, you are given two choices for the second guess: Up or down.
  - Up and down are 10x higher and lower guesses (making them adjacent ranges to the first guess).
  - If the second guess is wrong, you lose. No more guesses.

I wrote 10x and sqrt(10) to make a game literally about orders of magnitude, but you could of course you smaller numbers, like 4x and sqrt(4), to make it harder.