Tactics is about thinking about the scenario and coming up with a plan to resolve it in your favor. It depends on being able to have a clear idea of what's going on, and on what sorts of things would happen in response to your possible actions, by having a DM who explains the environment in a helpful way, and rules that actually dictate what's going on. Tactics includes things like: fighting a battle according to minis combat rules; building a flying machine using skeletons and immovable rods; figuring out how to steal a tank driving down the highway; short circuiting an adventure path weeks in advance by using contact other plane to google the future; and so on. Pathfinder 2 has the trappings of a Tactics RPG, with the many layers of rules for all sorts of things, but then it has the DM secretly make up DCs for a lot of skills, so the elaborate skill rules can't actually be used to form plans in any grand sense and only the basic tactical combat is really left.
Antics is about tactics going terribly, terribly, wrong when the players actually try to put them into action. Usually, the RPG stories that are exciting enough to actually tell contain some amount of Antics to them. It depends on hidden information, in the form of things the DM hasn't told the players, and in the form of unknowable things like the results of die rolls that haven't been rolled yet. The way that RPGs often have an aversion to auto-success even on things that really should be super easy for such a badass character seems to me like the designers realizing at the last minute that their game doesn't have enough Antics and trying to squeeze some in via comedy of errors at the last minute. Better antics come from more rube goldberg-esque hidden information than just a bad roll or two though, unless your bad roll does something really interesting somehow.
Melodrama is all the fluffy roleplaying stuff, like talking in a silly voice, thinking about how cool your character's whole aesthetic and powerset is, making your character do things that aren't actually good ideas because "they're what my guy would do"/"yeah, but my guy doesn't know that". If a game has too much Tactics and not enough Antics, any player can choose to help even the scales a bit by making a poor decision that gets the party in trouble. Yes, I did lump in most character-building people with the "roleplayers"
.There are many things people put into RPGs that don't really help increase any of these three good things. Tiny fiddly bonuses don't add much to the tactics and actively take time away from the antics and melodrama. Skill webs and other elaborate schemes to slightly increase realism at the expense of any form of balance are basically aiming to increase tactics while they actively serve to gut the depth of the tactical elements. Elaborate systems for character creation are fine, but only so long as careful reading of the rules allows you to discover new and interesting combos that you can then smile about melodramatically.
A fixation on not deviating from "the story" and letting each encounter happen when it's "supposed" to does allow players to achieve some tactics (in the form of presumably polished tactical combats, but not the more bizarre large scale logistical stuff), some antics (in the form of moderately botched negotiations, bumping into traps, fumbling about in combat), and plenty of melodrama (you don't have much control over what happens, but you still get to choose how your characters act when it does, and the combats give you freedom to show off how great it is to grapple people with dual-wielded scythes or whatever). According to TAM theory, all the core pillars being satisfied is why people like that stuff even though they could be reaching much greater heights of wackiness in terms of Tactics and Antics if given more freedom.
I think I might have rambled a bit there, oh well.
