I decided to write a blog about how survival systems work together in the game, first because they are quite interesting, and second they can be a bit complex. We are trying to mimic real-life mechanics as closely as possible without crossing into a simulation zone.

Author: Ali Yorulmaz, Technical Game Designer

First things first: Go Wayback! has a survival system that monitors and manages Lucy's vitals, and it’s directly connected to several other systems.

Now, Let’s Start With Survival Itself

There are three elements players need to keep track of to survive:

• Body Temperature

• Calories

• Water

Unlike many other games, these bars are not “Hunger” and “Thirst.” And no, they are not the same thing. Names matter; names have power. As Sir Terry Pratchett said, “You have to name the beast before you can kill it.”

So, What’s the Difference Between Calories and Hunger?

Simple. These are the burnable calories (carbs, proteins, and fats) you currently have in your body.

There’s one mechanic I hate most about survival games. You can starve for days, and then suddenly eat a burger you found in the trash, and fully recover instantly, as if nothing happened. That’s the difference between a hunger bar and a calorie bar. With a calorie bar, the longer you starve, the harder it is to recover. The same goes for water. And before you ask, by default, you start the game with enough food and water for three in-game days (if you stay in room temperature and don’t move): 3600 kcal and 6 liters of water.

Most Lethal of the Three: Body Temperature

Most players die from hypothermia. The human body operates best at 36.5°C. When you’re above or below that value, it’s bad, and can even be lethal in real life.

Body temperature is also tied to calories and water. When you have a fever, you burn through water faster because you sweat. When you’re cold, you burn calories faster as your body tries to warm itself.

As I said, we try to mimic real-life survival mechanics as much as possible, as long as it's fun. To make things a bit gamified, we shortened the length of a day. So you can go a little more than two in-game days without water, and about three in-game days without food.

Under normal conditions, when you are moving, jumping or running a fever, you burn water faster. When you are cold, you burn calories faster. Those extra burned calories slow down how quickly your body temperature drops. Multiple systems work in harmony to keep you alive against all odds. Well, to a degree, considering there are just as many systems working together to kill you as well!!

In a real-life situation, Lucy would suffer from alkalinity issues, confusion, greatly reduced muscle strength, and that’s just for starters. Even people on hunger strikes make sure to take in a minimum amount of minerals each day to function.

So how do we mimic these without making the game tedious and boring? The first step was to remove the stamina bar. (Yes, there was a stamina bar at some point.) Our map is huge, and while slowing the player for the sake of realism sounded charming at first, it quickly became frustrating.

Instead, the system now calculates your activity level and adjusts how many calories you burn. Very slightly, but in this game, even small changes can be fatal.

In-game, if your calories or water hit zero, you start slowly passing out. You see tunnel vision, the world darkening, and your heartbeat slowing down. This is a system I call Torpor. The tunnel vision and color fade get worse over time, and depending on your other vitals, you have up to two minutes to recover. But there is a catch. If you recover once, the next time you enter the Torpor state, your maximum survival time drops by 30 percent. So in Go Wayback!, what doesn't kill you makes you vulnerable.

Since some of the effects of hypothermia and malnutrition are hallucinations and confusion, I even experimented with randomizing the key input mappings to simulate disorientation. Then I tried it, hated myself for it, and removed it. But who knows, maybe one day we will have mirages of weather towers shimmering in the distance as hallucinations.

Remember: we’re trying to mimic real life, within reason. It’s still a game, not a simulation. But when you’re in trouble, ask yourself, what would I do in real life? Are you cold? Then wear an insulated winter jacket. Do you have a fever? Or maybe you’re overdressed in front of the fire? Does your body temperature drop fast after rain or jumping into a river? Yeah, wet clothes do that. You might want to light a fire and dry them.

Now, Let’s Explore the Connected Systems

Do you remember me mentioning systems working in harmony to kill you or save you? It’s time to dig deeper into that.

Since survival is not only about eating mushrooms, drinking water, and complaining, we have five major systems ruling over different aspects. Here is our pantheon:

FREY! God of Nature

This is a totally independent system, and it doesn’t listen to anyone! I designed it, coded it, and still, it doesn't listen to me. I know, how ungrateful.

It determines weather states and patterns, and we have no real control over it in-game. So, when you’re hit by a storm, followed by a very cold, clear sky, and you barely survive hearing the weather warning about an incoming blizzard, blame Frey!

As you can guess, world temperature directly affects body temperature. It’s essentially a tug of war.
Just like in real life, your body always tries to match the ambient or room temperature. By burning calories and sweating, your body regulates itself to about 36.5°C. The survival system follows the same principle, and your clothing helps, assuming it’s dry. Wet clothes? Not so much.

HEPHAESTUS! God of Craft and Building

Though we don’t have an actual building system in the game, he’s in charge of BUILDings, like cabins and shelters. Originally, he also handled spawning cabins and shelters, but now that’s managed by ShelterManagerV3 (yeah, I know, boring name, don't look at me, I didn't name it). What Hephaestus does now is manage cabins and shelters, preparing them when a player is nearby.

It also controls one very simple system. Airflow! <pause for the applause>

Each cabin and shelter has an airflow system that gathers data from Frey and Njord, and is controlled by Hephaestus to calculate airflow inside. Is a window broken? Is it boarded up? What’s the window’s orientation relative to the wind? Are the shutters closed? By the way, who left the door open during a blizzard?

It gathers all this data to determine airflow and its strength. Like the survival system, indoor temperature is a tug of war between the fire system and Frey. Frey tries to cool the cabin to the outside temperature, and the fire attempts to heat it. Airflow acts as the referee; lower airflow values make it easier to heat up the room.

Airflow values tracked by Hephaestus

The damage cabins take during storms also ties directly to this system. Boarding windows helps, but broken glass is not as effective as an intact window, though it’s still better than open air. Just keep in mind, planks may offend Njord, and he might start breaking them.

CROM!

When I first asked Scott about naming the item-spawning system, his first suggestion was Demeter, goddess of plenty. But after reminding him what we’re actually spawning inside the cabins, we settled on Crom, god of poverty and suffering.

Based on inputs from Hephaestus and ShelterManagerV3, Crom blesses cabins with loot. Sometimes it’s abundant and of good quality; other times, it’s a trick with low-value items and bad loot. I’m not going into the algorithm details, but there’s a logic behind it, and I’ll leave it to you to figure out what exactly influences loot quality.

Ok, so how does the system work? Each cabin has many possible spawn locations. When Crom blesses a cabin, it first judges its worth. If it decides the cabin is worthy, it blesses it with good loot like proper food, insulated jackets, gloves, or even a Fire Rod! If not, you'll just find a bunch of spoiled food.

This is an automated system based on logic. It doesn’t care about your character's state or what you were doing. The worth of a cabin and its location are determined during the loading screen.

Yes, it really blesses the cabins

NJORD! God of Wind

It determines not only the wind itself but also how it affects the environment. Have you ever noticed how the wind sounds quieter when you’re behind rocks? That’s Njord detecting your protection from its gusts. These are good spots to weather storms or blizzards, better than being out in the open, but not as effective as being inside a cabin.

Ah, before I forget, it's also in charge of destroying cabins, breaking planks and windows during storms.

KEL!

I’m pretty proud of Kel. It was originally intended to handle buffs and debuffs, but realistically, there aren’t many buffs we can provide. In the end we aim for realism. Just because you eat chilly peppers, you won’t magically develop resistance to cold. So for now, it only applies debuffs such as windchill, poison, fever, hypothermia, torpor and many many more to come. It monitors your actions and can curse you with a debuff for doing something you really shouldn’t, like overheating yourself.

Currently there are three types of debuffs:

1- Conditional debuffs, such as hypothermia and hyperthermia, are automatically triggered depending on your body temperature and clear themselves once the condition is gone, without any side effects.

2- Prolonged debuffs, like torpor, linger even after being cleared they have long-lasting side effects.

3- Stacking debuffs, like poison, which grow stronger each time they are applied to Lucy.

Hopefully, we will implement many more debuffs and buffs in the future.

Survived long enough to read all this? Impressive! Now go test your theories in the wild and tell us how it went, we’ll be waiting on Discord to hear your stories.