Conditional spawn

What appears (enemies, creatures, resources, events) is drawn according to the system's state: the hour, the weather, the tier, the intensity.

32 examples across 16 archetypes.

Every example recording conditional spawn, in chronological order, with the archetype's domain and the other parts the same game records.
Game	Year	Medium	Archetype	Domain	Other parts	How the system works
Dungeons & Dragons (Basic Set rulebook, Holmes edition)	1977	Tabletop RPG	Light Sources	Environment	Drain, Exposure	Dungeon turns are ten minutes. A torch burns for six turns and a flask of oil in a lantern for 24, each lighting 30 feet; without light humans and hobbits move at half speed or less, and artificial light attracts monsters and warns them of the party's approach.
Santa Paravia en Fiumaccio	1978	Video	Domain Management	Society	World clock, Population change	Each turn is a year of harvest, taxes and justice, and public works. Harsh taxes and unfair justice carry hidden penalties and drive serfs away, short grain raises the death rate, markets, mills, palaces and cathedrals raise tax revenue, soldiers cost 3 florins a year, and a death year drawn at the start ends the reign.
Advanced Dungeons & Dragons, Dungeon Masters Guide	1979	Tabletop RPG	Day-Night Cycle	Environment	World clock	Daylight is divided into morning, noon and evening and darkness into night, midnight and pre-dawn, and each terrain checks for encounters only at some of them. The city table has a separate night column that adds ghosts, wights and vampires, sends bandits in bands of 3 to 12, and doubles the watch.
The Oregon Trail	1985	Video	Survival Loop	Body	World clock, Drain, Exposure	The party eats from a shared food stock at a chosen ration each day. One party health value worsens with weather, pace, short rations and missing winter clothing, and poor health raises the daily chance, up to 40 per cent, of disease or injury. Hunting refills the stock at the cost of a day, with no more than 100 pounds carried back.
SimCity	1989	Video	Pollution	Environment		A pollution map tracks a nuisance level in every area, made mainly by industrial zones as they grow, by traffic and by coal plants. It lowers residential growth and land value and counts against the city score, high levels provoke monster attacks, and the remedies are dispersing industry and replacing roads with rails.
Civilization	1991	Video	Pollution	Environment	Treatment, Forecast	A city's resources, and its population after the Automobile, give nearby squares a chance each turn of turning polluted, 1% per smokestack shown. A polluted square halves its yields and costs 10 points of score until Settlers clean it in four turns, improvements with upkeep cut the chance, and nine or more polluted squares risk global warming.
Harvest Moon	1996	Video	Seasons and Calendar	Environment	World clock, Exposure, Forecast	Seasons last 30 days. Vegetables grow in spring and summer, grass lies under snow in winter so feed must be stored, and the mountains yield different wild goods each season. Festivals fall on fixed days, such as the Harvest Festival on the 12th of Fall, and the player has two and a half years to make the farm succeed.
Ultima Online	1997	Video	Simulated Economy	Economy	Demand	Every object drew on a fixed bank of resources that returned to it on decay. Players mined, hunted and crafted, and NPC shopkeepers priced goods from inventory, sell-through and cash on hand. Hoarding drained the bank, and the closed loop gave way to resources created at a constant rate.
Left 4 Dead	2008	Video	AI Director	Pacing	Return to rest, Intensity reading	The AI Director rates each Survivor's emotional intensity from damage taken, incapacitation and nearby kills, decaying it over time, and tracks the highest of the four. It sends full threat populations until a peak, then relaxes for 30 to 45 seconds; it also chooses which weapon caches and item groups exist and deals Tank, Witch or nothing along the route.
Left 4 Dead 2	2009	Video	AI Director	Pacing	Intensity reading	Valve describes AI Director 2.0 as procedurally changing the weather and the pathways the four survivors take, besides tailoring the enemy population, effects and sounds to the players' performance, so level layout, world objects and lighting also vary between runs.
Red Dead Redemption	2010	Video	Crime and Bounty	Society	Escalation, Return to rest, Paid reset, Report step	A reported crime brings a Wanted Level and a Bounty, and the higher they are the more lawmen join the chase. Breaking their line of sight ends the Wanted Level, but bounty hunters still come until the bounty is paid at a telegraph office or cleared by a pardon letter. Eyewitnesses can be bribed or killed before they report, and high honor makes them look away.
Minecraft	2011	Video	Day-Night Cycle	Environment	World clock, Exposure	Daytime lasts about ten real minutes. At sunset hostile mobs spawn wherever the light is low, and zombies and skeletons burn in sunlight. Mojang's guide answers the night with walls of blocks, torches crafted from wood and coal, mining through the dark, or a bed that skips to morning.
Guild Wars 2	2012	Video	Dynamic World Events	Pacing	Territory change, Headcount scaling, Contribution reward	Events pop up when something critical happens in an area, the log and map mark them, and anyone nearby takes part without grouping. Most scale with the players present, contribution earns a gold, silver or bronze reward, and outcomes chain, so a camp the players failed to save is taken by its attackers and a later event retakes it.
Don't Starve	2013	Video	Light Sources	Environment	Drain	A torch crafted from grass and twigs lasts 75 seconds and burns faster in rain, and fires need fuel. In complete darkness Charlie attacks after 5 to 10 seconds and every 5 to 11 seconds after, each attack costing 100 health and 20 sanity, until the player finds or makes a light.
Dead of Winter	2014	Board & card	Settlement Raids	Pacing	Capacity and load	Each colony phase adds one zombie at the colony per two survivors there, rounded up, one per survivor elsewhere, and one per noise token left by searching on a die roll of 3 or lower. Zombies fill the entrances in turn, a barricade stops one, and a full entrance kills the colony's lowest-influence survivor and lowers the shared morale.
Darkest Dungeon	2016	Video	Light Sources	Environment	Escalation, Drain, Exposure	A light meter from 0 to 100 falls with each corridor step and rises when a torch is used or the party camps. In five bands down to Black as Pitch, lower light raises stress, the chance of the heroes being surprised and the chance of extra loot, and at zero a hallway battle may become a Shambler ambush.
Stardew Valley	2016	Video	Seasons and Calendar	Environment	World clock	Four seasons of 28 days. Most crops, foraged items and fish are available only in their season, crops wither when a season ends unless they also grow in the next, and each season holds two to four festivals. A gift given on a villager's birthday earns eight times the usual friendship points.
Blades in the Dark	2017	Tabletop RPG	Wanted Level	Society	Escalation, Paid reset	After each score the crew takes 0 to 6 heat by its exposure, plus more for killing or a well-connected target. At 9 heat it gains a wanted level, and the GM rolls dice equal to that level on the heat column of the entanglements table, which reaches Arrest. Only an incarceration lowers the level.
CO2: Second Chance	2018	Board & card	Pollution	Environment	World clock, Demand	Each decade a region whose energy needs no green plant meets gets a fossil fuel plant, which raises the global CO2 track and costs a carbon permit or a fine at the market price. Cooperative players spend victory points to push the track down at a price rising each decade, and at 500 ppm every player loses.
Red Dead Redemption 2	2018	Video	Crime and Bounty	Society	Return to rest, Paid reset, Report step	Witnesses report crimes unless silenced, and the law searches an area marked on the map until the Wanted level fades. Serious crimes by an identified player add a bounty kept by state, which sends lawmen and bounty hunters and remains until paid at a post office or served in jail.
RimWorld	2018	Video	Settlement Raids	Pacing	Intensity reading	The storyteller buys raiders with raid points computed from colony wealth (buildings at half value) and colonists, multiplied by the chosen threat scale, a factor easing the first 40 days, and an adaption factor that lightens raids after colonists die or fall. Cassandra Classic sends major threats in 4.6-day on phases and 6-day off phases from day 11.
Pokémon Sword and Shield	2019	Video	Dynamic Weather	Environment	Exposure	As shown at Nintendo's E3 2019 demonstration, different Pokémon appear in the Wild Area depending on the weather, and the weather changes which Pokémon are effective in battle, a thunderstorm favouring Water and Electric types.
Animal Crossing: New Horizons	2020	Video	Seasons and Calendar	Environment	World clock	The game clock is linked to real time, so the seasons and the time of day follow the player's own clock, with a Southern Hemisphere option added. The insects, sea creatures and fish to be found change with the season and the time of day.
Factorio	2020	Video	Settlement Raids	Pacing	Escalation, Intensity reading	Biters attack only when the factory's pollution cloud reaches their nests, which consume pollution to send attackers, mustered every 1 to 10 minutes. An evolution factor raised by time, total pollution produced and destroyed nests brings bigger biters and spitters, and its rates are set at world generation.
Back 4 Blood	2021	Video	AI Director	Pacing	Intensity reading	Turtle Rock describes a Game Director constantly adjusting to player actions in a four-player cooperative campaign, sending tougher Ridden including mutated boss types. The director also adds Corruption Cards to the deck a run plays through, and the players must react to them.
Dying Light 2 Stay Human	2022	Video	Day-Night Cycle	Environment	World clock, Escalation, Drain, Exposure, Forecast	After sunset the infected take the streets. A Howler that senses the player starts a chase, and from April 2024 Volatiles take 2 to 7 seconds to recognise the player by distance. Experience earned at night is multiplied by 1.5, and some quests are marked as night quests.
Cities: Skylines II	2023	Video	Traffic Simulation	Economy		Citizens choose routes by time, comfort, money and behaviour, using every lane and switching lanes around jams. Accidents rolled per road segment block lanes until cleared, slow service vehicles let fires spread, and delivery vehicles' costs rise with distance.
Darkest Dungeon II	2023	Video	Light Sources	Environment	Escalation, Drain, Exposure	The stagecoach's Flame, from 0 to 100, falls while travelling and in drawn-out battles and is restored by helping travellers, clearing lairs and an item. Its bands set round-start tokens such as Blind and how relationships between heroes go; below 30 the Shambler may ambush, and at zero cultists attack, restoring 40 Flame if beaten.
7 Days to Die	2024	Video	Settlement Raids	Pacing	World clock, Intensity reading, Forecast, Headcount scaling	A Blood Moon horde comes every seventh in-game day by default, 22:00 to 04:00, after a red warning on the day counter. Its waves and zombie types follow game stage, player level plus days survived times a difficulty factor, with party members counted at diminishing shares. Heat from workstations and generators draws Screamers who summon hordes.
Dragon's Dogma 2	2024	Video	Fatigue and Sleep	Body	Drain, Costly rest	Damage lowers maximum health, which basic healing items cannot restore. Sleeping at a fixed campsite needs a heavy Camping Kit and risks an ambush that forfeits the recovery; a rest at an inn or house is safe and records a checkpoint save.
Monster Hunter Wilds	2025	Video	Ecosystem Simulation	Inhabitants	Agent needs, Population change	In the Fallow hungry predators roam for food and herds grow aggressive, an Inclemency brings the area's apex monster, and Plenty follows. The director says a hunter can lure a stronger apex monster to a herd so that the monsters fight and wear each other down.
Valheim	2026	Video	Settlement Raids	Pacing	Intensity reading	Every 46 minutes there is a 20% chance of a raid on a player standing within 40 metres of at least three base structures, outside dungeons. Which raids can come depends on the bosses defeated, from boars and necks at the start to drakes, fulings and charred armies later, and most end when the player holds the area until a timer runs out.