The idea of a "Tactical Combat Module" to me implies expanding the complexity of the existing combat rules, adding back in most of the options from previous editions, and then adding whatever new content the designers though would be a good extra.
This would include something like
1. Expanding the weapon list and differentiating them more (like in 3e).
2. Alternate Crit rules other than more damage
3. Tripping, sundering, and other combat options other than whats already there.
4. Beefier rules for verticality including flying.
5. Hex based combat.
6. Tactical mass combat.
7. An expansion on the Adv/Disadv system to encourage stacking multiple Adv.
I am one of those that do think that the designers bailed on their promise of adding in things removed with optional "modules". They have certainly added in things I consider "modules" (like ship combat in Saltmarsh) however it gets buried in with other content rather than expanded on and focused into a supplement in and of itself.
This about sums it up. Continuing with the perm advantage flanking advantage you have Facing That was originally another part of flanking that was originally offset by the old AoO rules
While the
were fairly simple for
movement, casting a spell or digging into your inventory would also trigger an AoO & many class/PrC features or feats would adjust what you could trigger an AoO off or what you could do with/without being subject to an AoO. Sure you can use the old AoO rules but then you are stymied by the fact that they extended the most magical container effect of a magic container
still in the game to any crude mundane container.
If inventory interaction were all it was then you could fix that too.... but It's
not that simple
Oops, but nothing uses those little tags so you now need to go through & decide which class & race abilities trigger an AoO & which don't while hoping you balance it right.
But don't forget that certain actions trigger them too
and many more I'm sure... But that's not it, you could do things that let you avoid those sometimes like so
or simply by casting certain kinds of spells
touch range spells exist with 5ft but touch attacks do not, where do you draw the lines.... are you as the gm prepared to rewrite all of this so far just to implement the rest of this one optional rule
(and are your players willing to play Bob's resulting self published rpg?)because WotC decided to remove everything supporting it from the & make it an "optional" but unfinished rule rather than keeping the support & making optional rules for container interaction spellcasting, full move speed, & so on don't trigger AoO's?
But wait, we aren't done.. Lets say you do all that... now you have all manner of feats that grant you other things you can make AoO's against, feats you can take to do specific things that would normally subject you to an AoO without being subject to them. We aren't done though, 5e has a lot of feats & class abilities that were once balanced by AoO's that are now balanced by the action economy so add all of those to the list of things you as a gm need to rebalance & fix.
Speed factor is another boondoggle that makes the GM's role hell. Just like that UA "greyhawk initiative" it only works if you run combat like an auctioneer. "who's got 20+, 19, 18, 15-17, etc" but given the lead baloon reception greyhawk initiative got & anecdotal evidence of how it was discussed it's far more common for gm's to run combat
similar to this.
As to some of the other ones?... I think you might be giving this too much credit
Pretty pointless looking rule since phb196 doesn't even mention that sorta cover from trying to shoot into melee But if you squint you get this
Unfortunately It's kinda pointless because hitting cover requires you to miss the target with a roll high enough to hit the AC of something probably in melee with it.
edit: if it was easy to simply port meaningful AoO rules into 5e we'd have a UA for it... but all the edge cases that need to be clarified would make it into a massive thing with a lor of balance concerns so we don't.