BIG OLD THOUGHT COLLECTION POST GO!
The setting of this game has gone through multiple iterations, and the current and likely final version has gone through some brainstorming both in my head and in Slack. The broad strokes of the planet are more or less figured, but not all of the finer points have been worked out.
In summary, this tidally locked planet contains a reasonably advanced, industrialized society that lives primarily along the terminal line where light and dark meet. It has not been decided if there will be multiple nations or not, but they don't have a lot of room to spread out, so cultures will probably be fairly similar unless you go maybe halfway around the globe. On that note, I've considered the possibility of two distinct nations, each with a capitol at the north or south pole (the only two places whence one can always see the moon as it revolves).
Regarding the level of technology and society, I'm keen on doing something akin to 1920-40's America, partly because it's something I don't see used very often (i.e., almost never) in games, and mostly because it seems like people were snazzier dressers back then. Regarding the level of magic, most fantastical elements for now are relegated to two things: the creatures that live in the wastelands of light and dark, and magic crystals (or an undetermined magic crystal substitute) from which people can draw power. I'm leaning toward this power not being used too widely in society. Electricity works just fine as an energy source, and it's much easier to come by than the crystals. Magic power is something to be used on a personal scale: combat, healing...perhaps decoration/art? The applications of magic are something to be considered further, but in game terms, they can be equipped in order to upgrade items or gain abilities.
Regarding time, I've given this more thought and integrated some ideas from multiple sources. The moon is the primary reference of time. When the moon emerges from being eclipsed, that is the start of a month (similar in length to an Earth month). Beyond that, time is most commonly measured by dividing or multiplying a month. For example a quarter-moon, or just a quarter, is about a week for us. Things like birthdays may be celebrated every ten months, a ten-moon. Based on something I read while researching tidal locking and also somewhat inspired by Legacy, I like the idea that the people of this planet never sleep, or at least not like we do. Since there is no night, and therefore no pre-established time set aside for long periods of sleep, the people could sleep maybe an hour or two at a time whenever they feel the need. This would also fit logically with how most RPGs work, where characters often tend to sleep only when they're injured (or the story demands it) and would still account for the use of "tent" items and inns at any hour of the non-existent day.
I briefly considered the idea of giving the planet an axial tilt that would still allow for the changing of seasons, but that could potentially interfere with some of my ideas for the story. Plus I've grown attached to the idea that the climate is constant in any given location.
On the story side of things, one big point I'm quite keen on is the idea that there are two primordial colossi slumbering at the brightest and darkest spots of the planet. How these beings will figure into the plot of the game is up in the air, but there are a few ideas going around, most of which involve people trying to harness or otherwise influence them for non-evil reasons that would result in a bad time for everyone everywhere. Perhaps some big company wants to use one or both of them as sources of theoretically unlimited energy.
One idea for the colossi that could go one of several ways is that even though they are presently dormant, they were both constantly on the move in the far flung past when the planet was not tidally locked and was thereby subject to a cycle of day and night. Some say that each was trying to either stay within the light or the dark and could never stop until the planet was tidally locked. Others profess that the movement of the colossi caused the cycle of day and night. Some fanatical group may wish to restore this cycle by reawakening the colossi. I imagine such a drastic change happening so suddenly would f*** up most of society, but can't you see? It's the way things are supposed to be.
It's worth noting that most people don't believe the colossi exist, but the idea of them is common knowledge.
This is somewhat going back to setting, but I will mention here that since the planet once had day and night, and people were not relegated to living along the terminal line, the rest of the planet is dotted with ruined cities that are either uninhabited or have been re-purposed if they're not too far out. Some people do live outside of the terminal line in the present day, though mostly these are scientists or resource-gatherers.
Since I was planning on implementing dialogue trees and a story that changes based on player actions, it's possible that the player could decide whether to disturb the colossi or keep things as they are. Brainstorming is still happening on this front.
The characters in this story were originally going to be members of a generic adventurers guild. Because this was originally fantasy-classic instead of 1940's science fantasy, and I needed something to throw my battle mechanics into but wasn't very creative about it. Now, the characters are members of a security firm...which is just my way of saying "industrial age adventurers guild" because I still haven't thought of anything better. xp They take contracts for various jobs ranging from security at local events to protecting caravans and labor forces leaving the terminal line and heading into the light or dark hemispheres. Over the course of the game they will receive multiple contracts from one of the brainstormed groups that wants to do something with the colossi. Once the characters figure out what's going on, they may have to decide whether to stop the plan or go along with it (whether for the money or because they believe it's a good thing to do).
I'm also playing with the idea of swapping perspectives between two groups of characters. It's possible that the two groups will start out with opposing ideas about the colossi, but if they come to some kind of agreement, they will join forces to make sure some plan or another fails/succeeds. It may also be entirely possible due to player choices that they don't come to an agreement, and you lose half of your cast as playable characters, instead gaining them as enemies if you made really unfortunate choices. Either way, having two initially separate parties could allow for a broader look at the setting from the multiple points of view.
As for the Soul System...I don't believe I ever described what that actually is. I said in my first post that I have a stat system unlike anything I can recall seeing in another game. To be more specific, other than HP and MP, characters only have two numbers that resemble typical RPG stats: body and spirit. These represent physical and magical abilities, respectively. Physical and magic attack and defense are derived from these stats but are not primary stats themselves. The numbers that define the Soul System are the three soul stats: passion, intellect, and temperance. Passion represents the strength of a character's emotions, intellect represents the capacity to analyze things logically, and temperance is the ability to balance the two aspects.
In battle, all characters and enemies have a gauge representing the present state of their soul, or their Soul Temperature. The hotter a character becomes, the more they are influenced by their passion, the more powerful their emotion-based skills become, and the more susceptible they become to the powers of intellect. Magic based on passion tends to be bright and fiery. The opposite is true on all counts as a character becomes colder. They are more influenced by their intellect, their logic-based skills become more powerful, and they are more susceptible to raw passion. Magic based on intellect tends to be subtle and icy. The affects of temperance are not entirely nailed down. At present, strong temperance makes it more difficult for outside forces to influence the state of one's soul. It may also mitigate the weakness to the opposing stat when one is very hot or very cold. I'd like to think of more uses for it. Plans for temperate magic and skills are limited since most characters are expected to focus heavily on either passion or intellect in battle.
Various actions can affect a character's temperature. Taking damage typically makes one hotter, while defending oneself or an ally may can make one cooler. Some characters will have skills that can tweak the temperature of their allies or enemies, perhaps by taunting them or calming them. If a character becomes altogether too hot or too cold, they could attain great power temporarily at the cost of losing themselves to the fight. They may succumb to a berserk lust for battle, or else fall into a state of emotionless calculation.
Opposites tend to be the most effective against each other. Hot attacks do more damage to cold targets than to other hot targets. Characters focused around the body stat tend to do more damage to spirit-based characters and vice versa. This should allow for straightforward party management, whether the player wants balance or specialization.
Outside of battle, the soul stats will influence your options in dialogue trees. Either your choices will be limited depending on your personality, or some choices will have a lessened effect if they go against your character's tendencies. For instance an impetuous character with a high passion score may have trouble making cautious choices, or an analytical character may have difficulty being spontaneous. You may also need to probe the personality of the characters you're speaking to in order to determine what sort of approach would work best on them.
One other soul-related mechanic I'd like to include may be contingent on how the party is formed. I'd like to include what I've been calling Soul Bonds. For those familiar the term, they're basically Social Links, and it's been really hard not to think of them as S.Bonds in my head. I haven't given much though to the specifics of how this would work in the current setting (it was originally designed around the generic fantasy guild setting), but during the down time between major story events, the plan was that you could take your protagonist around and have them interact with various characters to learn more about them and go on side quests to that end. As you bond with a character, they would get new abilities become able to perform dual techs with you. Or if they weren't a party member, you might get better prices at their store. Things like that.
Dichotomy is becoming a prevalent theme in this game. It started with the idea of passion and intellect representing hot and cold personalities, which grew into a theme of fire and ice. This inspired me to change the setting (which I was starting to not like) to a tidally locked planet. I didn't know the term "tidally locked" at the time, but I remembered reading a book that was probably written by Asimov that mentioned a planet that was half volcanic wasteland and half icy wasteland with a rocky but habitable band in between, and the concept of it had stuck with me.
Emotion vs Mind
Hot vs Cold
Light vs Dark
Good vs Evil sold separately.