"Juice" is probably a game design term you've heard before.
By Agricultural Research Service
Public Domain
It was first coined in the seminal article How to Prototype a Game in Under 7 Days:
“Juice” was our wet little term for constant and bountiful user feedback. A juicy game element will bounce and wiggle and squirt and make a little noise when you touch it. A juicy game feels alive and responds to everything you do – tons of cascading action and response for minimal user input. It makes the player feel powerful and in control of the world, and it coaches them through the rules of the game by constantly letting them know on a per-interaction basis how they are doing.
(emphasis mine)
The term is elaborated in these two excellent talks, "The Art of Screenshake", and "Juice it or Lose It":
"Juice" is a kind of polish, but a very specific kind -- excepting animation, it's nearly perpendicular to the traditional concept of "production value." Simply improving graphics, sound, and other measures of "quality" doesn't necessarily add juice, and vice versa. It's just as easy to imagine a richly rendered 3D game with lifeless interactions as it is a simple 2D game with garbage screenshots that positively bounces to life when you play it.
As Petri says:
It's impossible to give broad statements that are true for everything, but adding Juiciness to your game makes your game better 100% of the time, guaranteed.
;)
With that out of the way, I think there's another equally important kind of polish that doesn't get as much attention, perhaps because it doesn't have it's own term yet.
Let's call it Oil.
By W. W. Denslow
Public Domain
Whereas Juice is highly visible, Oil is really something you only notice when it's missing. A well-oiled hinge is smooth and silent, but a rusty one squeaks, groans, and annoys the crap out of you. If juice is all about making your game come alive and enriching interactions by maximizing the output you get for a single input, Oil is about minimizing the friction and effort that goes into making an input in the first place.
To put it another way:
Juice adds pleasure,
Oil removes pain.
But let's be specific. Just as the two talks on juice did, let's look at a bunch of concrete examples of how you can improve an existing design just by adding a few drops of oil.
Dragon Warrior
The original Dragon Warrior (aka "Dragon Quest I") has a contextual menu that you have to use to interact with everything. If you want to talk to someone, you walk up to them, bring up the menu, and select "talk."
If you want to open a chest, it's similar: step on top of the chest, open menu, select "take."
You have to choose a specific action just to walk down a flight of stairs:
In all of these cases, there is exactly one thing you can do with any of these objects anyway, so a single contextual "action" button would suffice. This is the path Final Fantasy took, which imitated Dragon Warrior in many ways, but added a few drops of oil along the way.
Talk to a character? Approach and Press A.
Open a chest? Approach and Press A.
Walk down a flight of stairs? Just walk on top of it!
Now, to play devil's advocate, Final Fantasy's single action button limits the available choices. What if you want the player to be able to search an innocuous looking floor tile with bones on it that happens to hide a secret treasure? Even considering this, the mandatory action menu is unnecessary - you can achieve the same complexity but still improve the experience.
My rule of thumb is:
If there is only one possible, unambiguous, non-regrettable action, the action button should just do that one thing.
Talk to the person. Open the door. Pet the puppy.
If there is more than one choice, or if the action is likely regrettable (rob the shopkeeper, smash the door, kill the puppy), then the action button should bring up a menu. If a player is standing on a tile with a skeleton on it, and they're not touching anything else that's interesting, and they press "A", it's probably safe to say they want to search that pile of bones (they're certainly not trying to "stairs" it). But if there's a treasure chest, and chests in this game can have traps, perhaps you should show a "open the chest?" dialogue first.
These things may seem obvious to us today, but it clearly shows how a few drops of oil can make massive improvements.
And speaking of Final Fantasy, it has some rusty hinges of its own. Let's look at that next.
Final Fantasy
We're in a shop and we want to buy some healing potions to stock up for a dungeon run. Here's the entire UI flow for that action:
Now do that 98 more times.
You have to push the A button three times to buy one healing potion, and there's a pause between each menu, so it takes ~1.5 seconds per purchase. That means buying a full 99 heal potions takes two and a half minutes of mindlessly mashing A. And Lord help you if you wanted pure potions or tents, because then you'd have to remember to push DOWN each and every time to select from the list.
Keep in mind that in this late-game scenario, I have 9,090 gold, and 99 heal potions only costs 5,940, so this is obviously something I should be able to do.
Notice how much better this gets with a single UI tweak:
It could be streamlined even further, but just being able to manually scroll the quantity up to 99 is a huge boost to efficiency and cuts down on a lot of pain.
Obviously the interface is only so clunky because of the game's age -- subsequent Final Fantasy titles improved on this and many other pain points -- but it stands out as a classic example.
Here's another example from FF1. Each turn, you assign actions and targets to each of your party members, in a manner still used in modern RPGs. However, there was a key oversight -- if an enemy happened to die before a character assigned to attack it took their turn, that character would simply wave their weapon in the air at nothing.
Players had to be sure to spread out their attacks to avoid "wasting hits", and to make matters worse, enemies had no vis
