Rain in Hyrule is the argument

A game is systemic when its systems can reach into each other, not when it has several systems running side by side. Rain in The Legend of Zelda: Breath of the Wild, Nintendo, 2017, is the clean case. Change the weather and climbing gets harder, fire fails, stealth changes, and the player plans the afternoon differently. The rain was not a skybox. It was a rule with friends.

Side by side is cheaper and looks like the same thing in a feature list. You have weather, and you have climbing, and they do not know about each other. Players feel the difference the first time they expect a consequence and do not get one. Systemic design is a promise that the world is paying attention to itself. Break the promise often enough and they stop experimenting, which is the death of the style. One interaction, honestly wired, is worth four systems that never speak.

A game is systemic when its systems can reach into each other instead of running side by side. Rain in The Legend of Zelda: Breath of the Wild is the clearest case: change the weather and most of the game changes with it.

Wet rock is harder to climb. Link's footsteps go quiet, so sneaking gets easier. Electric attacks hit harder, while fire arrows and bomb arrows lose the properties that made them special.

Some plants and animals only appear while it rains. Characters head for shelter. Campfires die. In places, large puddles pool and then burn off once the sun is back.

None of that is weather as scenery. One system reaches into climbing, stealth, combat, ecology, character behavior, fire, electricity, and the state of the level itself. That reach is the definition. The player is not walking through handcrafted scenes; they are working inside a web where objects, characters, environments, and rules all push on one another.

The web is made of two things: entities that can perceive each other, and rules for what happens when they meet. Far Cry states it bluntly. You can fight soldiers. You can fight animals. The part that matters is that soldiers and animals fight each other.

That fight is not a set piece delivered to everyone identically. It is a wildlife system and an enemy system colliding, because both sides register each other and both sides have rules for what to do about it.

Picture every entity with inputs and outputs. A tiger listens for the player, for bait, for fire, for guards. It also broadcasts its own presence for others to notice. Where an output lines up with an input, and the two can see, hear, or touch each other, a link forms.

Then a rule fires. The tiger mauls the guard. A flame meets a wooden arrow and the arrow lights. An exploding creature takes out a floor tile. Rain lands on a campfire and the fire is gone. Broad awareness, plus rules applied the same way every time, is the whole machine.

The first payoff is that players get to plan indirectly. Traditional enemies are usually aware of the player and nothing else, so the shortest interaction is the only one on offer: shoot them, punch them, or slip past them yourself.

Once the systems talk, the player can reach an enemy through something else entirely. Open a cage and let what is inside go for the guards. Draw two hostile factions onto the same street. Fold weather, a physics object, a fire source, or an AI routine into the plan.

One Watch Dogs 2 chase makes it concrete: police on your tail, you lead them into gang territory, climb onto a roof, watch the two sides tear into each other, and slip away while they are busy. It reads as smarter, and more personal, than shooting through the encounter.

That is the defining pleasure. The player uses the relationships between entities as the tool, and when it lands, they feel like they read the world correctly rather than followed instructions.

The second payoff is surprise. Systemic games throw up drama nobody authored as a single sequence. A three-way brawl between an army, a resistance group and a furious elephant. A fire that travels farther than intended. A guard investigating a noise that some other system produced.

These anecdotes stick partly because they have a shape. Plan, execution, chain reaction that ruins the plan, scramble to adapt. That is story structure arriving by accident.

They stick also because they are yours. A scripted set piece can be spectacular and every player still sees the same one. A strange collision of systems feels like something that happened to you specifically.

The name for it is emergent gameplay: solutions and situations never written as fixed events, which fall out of several systems meeting. The designer still owns the possibility space. They set the entities, the rules, and the conditions that let emergence happen at all.

Consistency is what makes any of this usable. First, a lot of entities need awareness: characters who fight among themselves, enemies who damage the environment, things that answer to the day-night cycle. Breath of the Wild layers a chemistry set on top of that, with wind, fire, ice, electricity, metal, water, and weather.

The more that can sense and affect each other, the more room the player has to experiment. But experiments only pay off if the rules hold. A player can plan only when they have a solid sense of how the world will answer back.

The rules also have to hold everywhere. If some wooden crates burn, every comparable wooden thing should burn. A rule that applies here but not there, for no reason the player can see, costs the world its believability and quietly teaches the player to stop trying things.

Abstraction helps a great deal. Rather than have each object watch for every other object, the game can deal in general stimuli: fire damage, piercing damage, explosive damage, sound, electricity, heat, water. Entities respond to those broad signals.

That is easier to extend, and it produces links nobody planned. Deus Ex players blow doors open with exploding enemies. Breath of the Wild lets metal conduct electricity into shrine solutions that feel like cheating, which is a large part of why they are fun.

A world that only moves when the player pushes it will not surprise anyone. If unplanned events are supposed to happen regularly, the world needs instability of its own.

Automation supplies it. Breath of the Wild's rolling weather drops a thunderstorm at the worst possible moment. AI characters carry their own goals and needs, so they wander, react, and bump into other entities without being told to.

None of this is an argument for chaos. Too much randomness makes planning pointless. The bar is motion: enough that arriving somewhere feels like stepping into a situation already underway, rather than opening a puzzle box that has been holding still, waiting for one correct input.

The target is a world whose rules the player can learn but whose consequences they cannot fully predict. Plans should be makeable, and they should sometimes fall apart in interesting ways.

Interconnection on its own does not get used. Plenty of games build the web and then give the player no reason to touch it.

Metal Gear Solid V is full of inviting options, but a silenced tranquilizer answers so many problems so reliably that the riskier ideas start to look like extra work. When one safe, direct tactic dominates, the possibility space sits idle.

Hitman pushes back by making Agent 47 poor in a straight firefight. Breath of the Wild breaks weapons, partly to pry the player off a favorite tool and toward improvisation. Both choices irritate people, and both do a job: they make the creative route the sensible one.

It helps, too, when the player's tools do more than delete entities. A kill usually subtracts relationships from the space. Hacking a security system, flipping an allegiance, throwing a decoy, starting a fire, moving an object, or pulling attention somewhere else adds relationships or changes their shape.

Strong systems get wasted when the mission around them is a corridor. Grand Theft Auto simulates city behavior, traffic, police response, and wanted levels well enough that actions ripple outward, and the wanted system is the sharpest part: harm a civilian and the consequences spread into police behavior and pursuit.

Then the main missions arrive tightly scripted, failing the player for not following an order exactly. Far Cry runs into the same split. The open camps are often more fun than the story missions, because a camp is a testbed for the systems and a story mission is a list of instructions.

Level design for a systemic game is less about laying a route and more about naming a goal and then caring very little how it gets reached. Open ground, several entities, overlapping awareness, and objectives with slack in them are what leave room for plans and anecdotes.

Every extra line telling the player where to go, what to do, what not to touch, and when improvising counts as failure is another square foot the systems do not get to use.

Systems need to be aimed at something, or they blur together. If every open-world camp has the same guards, the same animals, the same alarm, the same hiding spots, and the same explosive barrels, the interactions stop meaning anything in particular.

Tune them toward the experience the game is after. Far Cry 2 leans on spreading fire and roaming enemies to keep the player in peril and off balance. Hitman aims the opposite way, building a tightly choreographed social machine that the player exists to disrupt.

Rules can even carry an argument. In Mafia III the police answer crime more slowly in Black neighborhoods than in white ones. That is not background detail; the game is speaking through its rules and its response times.

So the useful question is never how many systems a game has running. It is what those interactions make the player feel, understand, risk, and remember.

Systemic design is not new; what changed is where it lives. Simulation games have long used interconnecting rules to mimic worlds, economies, ecologies, towns, bodies, colonies, and disasters from a godlike vantage point. RimWorld and Dwarf Fortress are famous for the absurd causal chains that come out of them.

Dwarf Fortress can kill a cat because a dwarf spilled alcohol on it, the cat groomed itself clean, and the alcohol poisoned it. Ridiculous, and a perfect picture of several small systems colliding.

The immersive sim took that kind of interconnection and put the player inside it, in first person, controlling one character. Thief, Deus Ex, Ultima Underworld, and System Shock are the lineage, and later games such as Dishonored and Prey carried it forward.

What feels different now is how far the idea has traveled beyond that lineage. It turns up in big-budget open worlds, in unusual European RPGs, in indie games made by immersive-sim fans, in stealth games, in action games, and in a modern Zelda adventure.

That spread is worth being excited about, because systemic design hands players room to plan, to watch the plan meet the world, and to improvise when everything breaks. You cannot settle it on paper either: you find out by getting the build running and playing it, and your own reaction is the verdict. The more games construct that interconnection on purpose, the longer their worlds stay in people's heads.

In the Flockbay app, pick two systems and make one change the other. Rain, or an equivalent, should alter movement or fire. Play until you use the interaction on purpose. If you never do, they are still side by side. Wire them or stop advertising both.

An AI adventure game maker and an immersive sim template are where systems are supposed to talk. One interaction first.