I added Speed Only to the leaderboard, as of right now the rules are simply only speed up and speed down are allowed, 30 Lives and Extra Credits codes are allowed. Things I have potentially up to change are whether the following are allowed: speed down powerup, 30 Lives code, extra credits.
If you have any opinions or know of any runs that would fit in this category please post them.
Additionally, I already checked and it is possible to complete this challenge on Arcade difficulty, good luck if you want to try. :)
Here's some reasoning for/against each:
Speed Down: This is NOT a required powerup, but you get a similar effect by dying to go back down to 0 speed. Additionally, only 2 speed ups are required to beat stage 7, and so continually using speed ups after each death already uses more than the 2 solely required powerups.
30 Lives: Makes finishing runs more likely, but takes more deaths to get the first game over-continue saving time over not using it.
Extra Credits: This is solely for finishing runs, I honestly see no reason not to allow this.