Hey, thanks for playing! I wanted to keep it pretty short for a jam game so I'm glad it finished I under 20. As for the MAX button, it's definitely bugged after a certain point, I'm still figuring out how to fix it lol. Glad you had fun!
I couldn't finish the game because of the overflow error :(
Like aguydude said you can use 64 bits (long and ulong types) if you're using integers, that will get you a long way (har har). Alternatively you can use float, up to 10^38, or double, up to 10^308.
Pretty simple game but still fun for its duration. Keep it up!