The next update to Pilgrimage includes soul and possession mechanics. And I ran into an interesting problem. How do I keep player agency while also allowing possession? The solution: Turn it into a fight.

At first, I thought I would just not even show the player that they were possessed because player agency is important to me, but I realized that hides such an important part of the simulation.

A little background.

The next version of Pilgrimage includes souls. Souls determine motivations in the world sim. They don’t include attributes or skills (and this is to keep a distinction between the soul and its host body).

All species have a soul defined for them, and some souls are weird. Some souls have the ability to possess others, either when their host is killed, when they are exorcised, or through haunting events (e.g., a person’s soul can possess someone in the region where they died).

Each soul is almost like its own individual, defined separately from the historical figure (which is the body). When you are possessed, the soul is added to a list of souls associated with that body. And they have different levels of control, they cannot clone themsleves, they only move from one body to another.

Every day, the souls fight for control and roll against each other, and one of them is determined to be the lead soul for that day. This happens both in the simulation and in-game. When that happens in the world sim, that’s the end of it. That soul makes all the decisions that day. Whether to fight, who to fight, whether to try to exorcise someone, etc.

But in-game, this introduces a problem. If I just gave the soul control, the player would lose control. But there’s an interesting philosophical issue with that. Who even is the player in the sim? In fact, it even says so-and-so was possessed when the player controls them. One idea I had was to give the player their own persistent soul that they move through lives. But I realized that’s too meta, and kinda boring, right? At that point, it’s just you.

So instead, the player is above it all. They don’t actually have a soul of their own. But their body? Their body has a soul, or even several if it’s possessed. So I decided to turn this into a popup, similar to ascension. Something like, “So-and-so (the soul’s name) desires blah blah blah.” Then you’re presented with a choice.

You can resist the soul, which triggers some rolls to determine whether you successfully resist its influence. If you fail, your character does what the soul wants. If you succeed, you get your normal list of actions.

Or you can give in, which automatically chooses an action based on what the soul wants.

This introduced its own problem. It would turn the whole game into a battle between you and the soul of the creature you’re currently living inside. That’s also kind of too much, right, like, it shouldn’t always be so intrusive to the player’s immersion… And it makes it really obvious what’s going on underneath it all.

That would be kind of cool if I were Deltarune, but I’m not Deltarune.

So instead, only parasitic souls trigger this. (A “parasitic soul” is one that can possess others, which is different from, but sometimes is, the soul of most species.)

Non-parasitic souls, however, just say what they want in that case, like “You feel the urge to fight the blah.”

Which I think is a good middle ground.

It’s funny that Deltarune devoted a whole game to exploring this concept, but it’s just one of many mechanics in Pilgrimage.

Later on, this will allow for things like ATLA-style Avatar cycles. And it already allows for interesting demonic possession, while also making wisp gameplay more interesting (because now all wisp souls are parasitic and have distinct personalities :3).

This will also allow for dynamic afterlives that are different in each world. Imagine a giant ocean of souls that just exists somewhere and gives them bodies, but doesn’t affect the historical sim directly.

Imagine if you’re possessed by multiple demons. That creates real tearing within you and real, split motivations that you’re always fighting against.

And it’s already in the repo for my Middle-earth world! The One Ring is treated as a parasitic soul! And so now it can influence you and other people if you have it and passes between characters.

Wisps were honestly pretty boring to play before. But now that their souls are parasitic and have their own personalities, playing as one means constantly dealing with the desires of the soul inhabiting your body. The very thing that would make ordinary gameplay annoying becomes the defining feature of playing as a wisp. :3