Thanks for your insights! I am glad you appreciate my over the top high score :D
With what you answered regarding the "2x on nothing" and "15p/unused spin", I must have misgauged that the numbers were not accumulating. I didn't do any exact maths, just didn't behave/ snowball like I expected it too :)
For the 2x on nothing, could it at least be that only the base score keeps doubling, not your total score of base score plus the additional 50s?
Yeah, indicators/ counters on screen would resolve this for sure, though I also find it appealing that you have to keep track of past decisions in your head.