I started thinking about the HackMaster 5e Feat of Strength and Feat of Agility. In essence, they are replacing old fashioned ability checks but adjusts the curve a bit. Take a look at the following chart.
Under the the classic roll equal to or under scenario.
Ability is d20p+ability score is higher than d20p.
Feat is d20p+"feat of " score higher than d20p.
Under and Ability are too linear (excluding the lumps) for my tastes and therefore kind of boring. Most folks are going to have average stats, so only the middle portion is going to be super interesting and lo and behold, the Feat category has the best curve. My proposition is simple - replace all ability check activities with Feat Of checks. It is a simple mechanic that works all over.
Saving Throw vs Magic
The saving throw modifiers are significant;y smaller than the feat modifiers. Additionally, they only apply to saving throws vs magic of a particular type. Therefore the saving throws can remain unchanged. It already works. I do miss the variety of saving throws from old school D&D but I don't believe this is actually any sort of flaw or problem.
Saving Throw vs. Poison & Disease
For whatever reason, this one in HackMaster 5e is different. Roll d20p+Con vs. Virulence (a set value). This produces a pretty boring curve, so why not chance this to a Feat of Constitution? Because honestly it gets into some complicated math that I really just don't want to deal with. I haven't used enough poison and disease to get a good feel and honestly, if it ain't broken (and I doubt it is) then don't fix it.
Feat Of Ability Difficulties
|That leads to the question of How to assign difficulties to Feats of Ability. Without a lot of fancy math, some guidelines based on average ability scores can be seen on the table to the right.|
I haven't used this in play, but it is, overall, a simple unified mechanic. If a PC is showing off their new haircut, Feat of Looks to see if anyone is impressed. Having a philisophical argument? Feat of Wisdom ... or even feat of wisdom vs feat of intelligence. For that matter, Strength vs Dexterity could be used in a wrestling match, Charisma vs Intelligence to charm someone trying to not be charmed.
The Feats of Ability could be combined with the characters skills (add the numerical rank 0 - 5) to the feat roll. and voila. Natural ability gets you pretty far, but some actual training and skill really puts it over the edge. That might devalue skills too much, but it is worth thinking about.