Yowza! Nice to read a much more comprehensive and well-thought out post on the structure of skills and skill tests than I had.
This mostly addresses the issue I have of slipperier slime at higher levels. The conclusion that Mike makes is that slime is indeed slipperier, but not necessarily for higher level characters, but in fact for 2 different characters.
So my mutant skink with PP 30 and athletics and acrobatics will find the slime less slippery than your mutant buffalo with hooves and enormous size? Not a bad solution, but it makes me do a lot of math on the fly, since I pretty much have to calculate where on the difficulty curve I want the roll to be for each roll. But on the other hand, I could just use the number of ranks/bonus points that a character has in a skill as a general guide to how good they are at it, and use that to determine what their difficulty is as a flat d20 roll.
Actually, I like that, let's run with it.
And speaking of running with it, let's steal some more - this time from Vampire 2nd Edition.
I always liked how you combined 2 things, attributes and skills, to determine how good the character was at a given task. So I will be asking characters for 2 numbers, attribute bonus and skill score, adding them together and using that number to determine how good the character is at the skill in question. Based on that, I will determine what the player needs to roll on the d20 to succeed at the task. Potentially the overall difficulty would also be modified by people helping and other factors (like, is somebody shooting at you).
Let's try an example and see if it works in concept.
Slinky the aforementioned Mutant Skink has a score of 4 in athletics (3 starting plus 1 bought with skills) and a modifier of +6 for PP, giving him a total of 10. 10 I would rank as pretty fracking great at a given skill, so to run across the slimy slime, he needs to roll a 7 or higher, giving him about a 70% chance of success.
Herbi the Buffalo, though - he has an athletics score of 4 as well (starting 3 plus 1 bought with skills), but only has a PP of 16, for a +1 modifer, plus he has a -2 because he has hooves. Total score 3. Which I would rank as intensely mediocre, but not pitiful, so he needs a 15 or better to run across the slimy slime. About a 20% chance of success.
I think I like the basic idea. It means that characters who are exceptional can have a reasonable chance of success at something even if they have no specialized skills in that regard, and characters who have such skills AND exceptional attributes have a very good chance of success at something, which is as it should be.
But this means that I have to rebuild the TMNT character sheet. Which I was pretty much going to do anyways.