Rules Omit (Exercises You'd Rather Not Bother With)
This is based on an original post by Jared Sinclair, at https://jared.blot.im/rules-elide-and-its-consequences, but at the time of this writing it's not accessible so shrug.
Off the top of my head, a core thrust of the post was that "rules elide" and that's all that they do. There's an example about lockpicking, there's going on to explain that you're discarding the things you don't care about to focus on the things that you do, but that's the thing I want to explore with examples. Examples that perhaps go a step beyond "I elided lockpicking by involving a die! I don't care about picking locks." and move on more into "I want to make the decision to pick a lock, because THAT matters to me, but the actual mechanics and negotiation of that are not something that fascinates me."
A messy prelude:
So, when you play a video game, you can only do what the game lets you do. There are finite possibilities, extremely finite ones in fact because you can't just throw any input into there. In a tabletop game, or any other game of shared imagination, it's absolutely the OPPOSITE. There are infinite possible gamestates, and infinite ways for one to go to the other, but without rules you have a lot of shit to trudge through.
It's easier for me to start from a rules base that already exists to explore this preliminary case. Lets take D&D, it doesn't matter which edition because we're talking about the equipment prices. They're all right there, so we just elided having to haggle about the fucking price of a candle. Nobody wants to haggle over a longsword, it would make spending your starting money incredibly tedious and arbitrary, it would waste your time and there's no point. So, instead, a longsword is 15 gp! Cool, we just elided having to negotiate the price of a longsword. Now, we can play the game we want to play, which is being shrewd with our budget and deciding on our equipment, not arguing about a price. It all goes like this, is what I'm saying. The rule gives you an answer, or it arbitrates something, which leaves you free to make fun decisions while the game does the lifting.
THIS, I can confidently say, is how all rules work. Just like fasteners fasten, and do not do anything OTHER than fasten, though they can erect all sorts of structures and assemble great contraptions. So too, do rules merely cordon off possibilities and limit the infinite by drawing arbitrary lines in the sand. Not a negative thing.
So, what does it mean to leave behind the "stuff we don't want to do" with rules, implying rules cover only things we don't care about, and then move on to the "stuff we want to do"? How can that be, if we are playing a wargame all about combat, and love the combat, and care about the combat? Surely it is absurd that the rules are covering something we "don't care about"? Well, not so fast. Refer to that example above: we LOVE buying weapons, and armor, and dig equipping and doing a loadout-- we just don't like defining what stats weapons have, or what their prices are, or our starting gold. That's shit we want out of the way so we can get on with it.
Combat is largely the same. We don't want to negotiate how much health our character is, so we roll for it -- OR, we're playing GURPS, in which case we DO want to customize how much health our character has. But, we don't want to negotiate how "special" our character can be in GURPS, so we have 150 character points. We don't want to arbitrarily decide how much every advantage is worth, so they are already listed out. What we WANT to do is build the character, and THAT step hasn't been done yet: that's what it means when the rules stop just short of the part we care about actually doing. It comes down to your judgement, decision making, choices and consequences after all.
Example 1: LANCER
LANCER arbitrates shit left and right, because none of that little stuff is important! This is a game about moving your mech around a board and choosing which prick to blast or hack, as well as weighing up options in battle and building a mech before the mission.
Negotiating how much you can load your mech with? That's right out, it's defined in the rules. Payment for missions? Nope, that's entirely arbitrated. Training? The level system disregards it. Physics? The game outright doesn't give a shit, the rules define the space you have to make decisions in.
The game, in this case, comes down to building your mech and making tactical decisions, which it's a pretty damn fun game of doing. It's not a game about the consequences of long term damage on your mech or the maintenance of your mercenary company unless you cruft that shit in and rip assumptions out to leave yourself the space to play.
Example 2: D&D
D&D's got a funny case of making a system full of rules that... don't really close off enough possibilities to make one distinct game; instead the last step is left for the GM to bridge. And sometimes they don't, and they keep a lot of aberrant shit in and end up playing the game they don't really want to play. Funny how that goes! But, an example still.
The classes? They cut the infinite down to a few archetypes so you can have an easier time choosing, and don't have to manage much shit and just focus on the adventure and the outfitting and etc. You know what D&D is. Just apply this lens: whenever you encounter a rule, think about what it's leaving up to you and what it's taking care of for your convenience. Attack rolls determine whether you hit or miss and how bad the blow is, while your Armor Class determines whether or not you get hit, but it is left up to you whether you're attacking or retreating or starting a fight to begin with. Your judgement calls are there but the system underneath you is handling all the consequences.
Skill checks are one that varies a lot over time. Some people don't want to go through the rigamarole of searching for traps, declaring how they're molesting the doorframe they're checking for traps, trying to negotiate with the GM exactly how they're checking a chest for traps, especially when they'd rather just have made the executive decision to Be A Badass Master Thief at some other fair opportunity cost. For them, they'd love to just make a d20 roll, that automatically gets raised to 10 if they rolled lower, which is then pushed upwards by a fat modifier. They still get to make calls about what they're spending their time doing when exploring, but they don't have to describe their searching methodology because it's boring to them. In this hypothetical.
For some, that shit is annoying. They would not prefer a treatment where they throw a die at a situation where proper deduction would home in on an answer. This is where it helps to just drop a rule and get elbow deep in the problem on occasion; Even the guy that prefers rolling perception will eventually say "hey, how can I miss it? I know it's down here." Again, it's all about what level they want to be playing at. Do they want to be on high, controlling the character with their fundamentals already described by numbers and stats? Or, do they want to be deep in the muck, making the detailed calls and hoping they don't make a dangerous mistake in how they approach the situation? Whichever it is, they use rules (and rulings) to omit the other modes of play and focus on the one they want.
A quick note on magic: You don't care about determining exactly what a fireball does, so the fireball is defined for you. What is up to you is whether or not you use it!
Example 3: Mothership
I like this example because it is a fun way to explore the "rules handle what we don't care about so we can focus on what we do" precept: Mothership is very horror-themed and as such, there's a rule for your characters to get stressed the fuck out and have episodes of panic. Obviously, you care about your characters panicking, but... imagine if that was up to you to decide? If it was a part of play that you could decide "Nah, I'm not panicking right now. That would be inconvenient, wouldn't make much sense to choose to do that... but the game is really flat otherwise..." Clearly this strawman player wants to deal with their character flipping the fuck out saying "Game over man, game over!" but they want to remain immersed and focused on their player agency. As a result, the rule is designed such that stress, and panic, are handled for you. Or rather, their accumulation is handled for you. The part you love to play, being the nervous wreck? Well, the game can't do THAT for you!
Example 4: whatever crunchy game you can think of where the rules totally don't elide anything. GURPS tactical shooting. Phoenix command or something. Pathfinder 2e.
Just look at the part you are doing in game, and think about how it was set up by the rules and designer creating the context for you to play in by stopping the rules off where your decision making process takes over. Huge feat list? Designer chose what wasn't an option. Deeply simulated combat? Designer already defined the variables and formulae for you. Part of the game for you is now having to pick up where the math drops off.
In conclusion: by limiting the infinite and defining what is left for the player to make decisions about, the rules in a system leave that space for the game you want to play by preempting the shit you don't want to play out.