1: Racial/Class specific feats.
I'm always torn about this. On one hand, cool racial feats feel awesome, and help make sure your tiefling or elf is a really awesome tiefling or elf. Showing them as a true paragon of their race that does things no other race can really emulate.
On the other hand, it could potentially make powerful combos more powerful (Half-Orc Barbarians now get XYZ that makes them better at being barbarians than any dwarf barbarian?) and quite a few people pick race for aesthetic and mechanics later, and locking people out of interesting abilities because they don't have the right blood is always something I'm a little leery of.
5: More mounted combat.
6: More underwater combat.
7: More aerial combat.
Aren't these a little tricky? I admit we have a small chicken and egg problem, but I've never even attempted to run, nor have any of my players had interest in mounted or underwater combat. It could be because there just aren't enough fun and interesting rules for it, but it seems to be one of those sections of rules that is difficult to do well without making them more complicated, and they will probably never see as much usage as normal ground combat rules.
10: They are game designers. How about something we've not seen before?
"Name me a color that doesn't exist", forget the poet's name but it went something like that. We've seen a lot, if you've read and gamed as much as I have (and I bet you've easily got at least two decades on my measly amount of experience) then you have seen a lot of mechanics and a hundred times as many themes and ideas.
Coming up with something never before seen is going to be a tough bar to beat, especially when there are things we've seen before that we'd like to see here.
11: Will post more when I remember them.
Somethings from my own list
More comprehensive crafting rules, making use of proficiency and giving us some ideas for unique, fantasy materials and ingredients that can be used in this new subsystem. Which herbs do you need to make a healing potion? Where do the grow? I'd settle for a lot less, because it would essentially be almost an entire book on it's own, but tool proficiencies seem like they want to be important and they just aren't so I'd love some work in that area.
Titles and "prestige classes". Watching the Running the Game videos by Matt Colville has really got me hankering for some mechanics for what happens when you earn a title, which literary characters do quite a bit, and I always have my players looking for new powers and abilties granted to them by legendary figures (at least one of them is just powergaming, because his way of dealing is "Hey, can you give me this cool thing because I'm awesome" but I digress). What would happen if you become the Champion of the Winter Court? The King's Champion? I can make stuff up, and am planning to, but getting some official versions of this could be kind of cool, mechanical rewards for good story.
