Extra Info : Technically, you can't reach 2.1B max limit high score ⛔️. The game will freeze once you hit the max limit‼️ (running score + background outstanding score can't larger than >2.1B)
With the Billy + Super Hooper + Shared Perks glitch combo, the bonus score points is running too faster than usual.
Even you paused the game, you still can hear the sound of Perks activation and bonus score on going calculate at the background.
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If you want to achieved nearly 2.1B High Score, you have to end the game in advance 300M to 400M score points.
Depends on your Multipler in the run.
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With Multipler x20, your screen display the score points is 1.6B, but actually you still have the outstanding bonus score haven't finished the calculation, pending at background.
Current display score 1.6B, with Multipler x20, you will have 400M bonus score still pending at background calculation.
Hence you must end game while screen display 1.6B, then during the final score calculation, it will automatically sum up the pending 400M score points.
1.6B + 0.4B = 2.0B ✅️
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If you continue playing the game reach 1.8B+, at certain points, the game will freeze, due to over 2.1B max limit.
1.8B + 0.4B = > 2.1B ❌️
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This is my own experience, I already failed 3 times before I achieved 2.07B successfully (without game freeze and crash).