Not sure if this would be helpful to anyone, but I made a simple table showing how to get the secret levels without necessarily giving away how to solve them.
I gotta say that this has been a fun experience, contributing to a community walkthrough like this. Hats off especially, though, to Swindle (and her husband) for cracking the secret levels. Usually I would have been a little upset about someone spoiling the secret, but like Unleashed, I don't think I would have ever figured it out. They're deviously complex!
Thanx for solving the puzzles @swindle333! Finding some codes was my easy contribution, but you did a great job in solving the puzzles, which I would have had an incredibly hard time with! *tops hat* Again, awesome effort!
This Sum Points Walkthrough (Level Guide) is now officially featured in the Sum Points game's comments for other gamers to use when stuck on a level! Great job everyone!!