HIDDEN MECHANICS

I think the one mechanic you never have to explain is the RNG - chances are that the developer doesn't know how it works.

What's mostly important is understanding what mechanics are there and what purpose they serve. While most RPGs tend not to explain game mechanics to players, how much of a problem it is depends on whether your game is very simple (like Dragon Quest) or very complex (like Nethack).

Hmm, here's an example from UOSSMUD, one of my games, and how I made the decision.

UOSSMUD has a class change system. Different classes have different stat bonuses. Knight has bonuses to attack, pdef, mdef, HP, MP, block, and evasion for example. Monk has bonuses to attack, strength, agility, pdef, HP, block, and evasion, but it has higher HP, attack and evasion bonuses than Knight, and lower pdef and block bonuses.

There's no tutorial explaining this. The player can see in their status screen which stats are being increased by thir current class, if they look, but they can't tell by how much. There's no easy way to tell that monk gives more attack power than knight. In fact, attack, magic power, pdef, mdef, block and evade are totally invisible stats that the player can't see anywhere (they are actually derived stats based on the player's strength, wisdom, agility, vitality and willpower, which are visible). This is further complicated by the fact that the stat bonuses given by each class increase as you level up - Knights get +30% HP at level 1 and +45% HP at level 100. After level 100 the stat bonuses stop growing; another thing players aren't told, since they aren't actually told that they grow in the first place.

This whole system is pretty complex, which is the main reason there's no explanation given to players. The format of the game also makes it very hard to give any more tutorials after level 1, since it is a nonlinear open world game. But really, the biggest reason is that knowing this info wouldn't affect their decision-making in any meaningful way. There are cases where not knowing something can cause the player to make bad decisions, but this isn't one. The classes all have different abilities, and normal attacks barely exist in this game, so the player already knows every job is different. Knight and Monk do different things. It's enough for Knight to be better at knighting and Monk to be better at monking. The numbers behind that don't really matter that much. If we displayed all those numbers and bonuses, players would take an extra 15 minutes figuring out how to optimize each new setup they changed to, instead of just playing the game, and there would be extremely little difference in their power. Unfun.

Ratty524
Does Final Fantasy tell you the damage calculations of your basic attacks? Does Mario give you an explanation about the fine details of how its jump physics work?

Learning those help you become better at those games, but they are not pertinent to playing the game itself. That being said...

ACTUALLY.

FF damage aside (they have horrific calculations anyway), I'd posit that Mario DOES tell you the fine details, through intelligent and purposeful level design. You must master the physics by the end of the game in order to make it through.

Rhyme
Due to the nature of the hidden mechanics themselves and partially due to my aversion of trying to include walls of text in the tutorial, they tend to never get noticed and not many players take advantage of it. When they do notice it, sometimes it gets disregarded as a coincidence.
It's always something I've been wondering how to deal with well, without over-introducing all sorts of un-necessary mechanics that may or may not be important but might help the player progress easier if they are aware and can take advantage of.

Gonna use Tales of Zestiria as an example. The game is based on the fighting game genre in a 3d playing field. There are a LOT of little techniques you can use to get ahead, like knowing when your combo ends (leaving you open), knowing when to block or evade, understanding that your SC (MP) bar being full increases your damage, etc. etc. etc. Again, there's a lot. Buuut there's four ways that it tells the player all of this information!

1) Tutorials. The early battles, naturally, have big prompts that come up explaining what to do. This is pretty standard. The same goes for the game's other core systems (fusion, the skill grid).

2) Character interaction. By investigating an enemy mid-battle, your characters will comment on it and its attack patterns/weaknesses/etc. For normal enemies, killing one successfully will unlock a second comment that's even more in-depth. This is all described within the character's way of speaking, of course, making it fun and easy to comprehend instead of just INFO DUMP. I'll show some screenshots when i get home

3) Monoliths. These are big stone tablets scattered across the dungeons, towns and overworld that give you permanent pages for your in-game strategy guide, which you can pull up any time outside of battle/cutscenes. By giving you the info in tiny chunks, and by storing it in an easy-to-reference guide, you can learn the more "hidden" mechanics bit by bit to incorporate into your gameplay.

4) Battle Actions. These are passives that you must consciously equip, allowing you to opt-in to more advanced mechanics, or instead spend your AP (think FF9 passive style, but for the whole party) on crutches/handicaps to help out. For example, by equipping Greater Heights and Something Else (i forget), you can chain your skills/spells together by holding down a button. It requires knowing that chains into what and having the desire to actually do so, but it's very useful. Having the player actually tick a box to opt-in makes it that much more conscious and pertinent.

so yeah. small chunks over time! i try to do this with most of my games, most recently (...yesterday...) with the sheep in RAMSFORTH. saving sheep lets you talk to them in the pasture, and some give you hints on how to maximize your battle effectiveness.

as for actual hidden mechanics I use? i try to be as transparent as possible without inundating the player. i can't think of any, really. i love counters and gauges so i just show everything on the screen!

In my game (RMXP), both strength and dexterity contributes to physical damage. I will tell the players that, but I will not tell the players the exact damage formulas. Strength will be more important than dexterity against enemies with high defense while the opposite is true against enemies with high evasion. Again, I will tell the player that, but not how exactly the stats work. This amount of information is enough for the players to make informed decisions and the exact formulas will not be helpful for the majority.

I prefer this approach in general, if X is going to be a thing, tell the player so, but skip the details.

I've beaten pretty much every generation through Diamond and Pearl and I've never made use of the IV/EV system (hell, I'm still not completely sure how it works). In fact, the only groups of people (that I've seen) that care about such systems are competitive players or selective breeders. If your game has those kinds of hidden mechanics, then explaining them really depends on your target audience. To me, sticking NPCs that give hints of these systems will be fine, but making a mandatory tutorial of them is a no-no.

You could possibly deliver mechanics tutorials in the skill descriptions. For example, "Fireball to one enemy. Inflicts Burn, which causes damage over time." It's short, sweet, and teaches players how the game works one fragment at a time. Later skills probably don't need this, but this would be helpful in the beginning. Keeping those early skills through the late game can double as a quick reference if players need a reminder of what certain mechanics do.

To use the EV example, assuming I understand how it works, when viewing a Pokemon in the Pokedex, you could have a section listing the EV points it gives upon being defeated. Couple that with an explanation from an NPC, and players that care enough should be able to figure it out. But yeah, "tryhard" mechanics can be pretty tricky to explain, and the longer I'm writing this, the less sure I am that this is a good idea. Hm...