Kerbal Space Program

This world is experimental. Only the default (Normal) difficulty has been thoroughly tested. Only vanilla (unmodded) KSP is supported - no part mods, planet packs, or other gameplay mods have been tested. The Making History DLC is supported and its parts are included by default; if you don't own it, opt out via the Enabled Part Packs option (see Key options) so the seed only uses stock parts. Kerbal Engineer Redux is known to work and is recommended for delta-v readouts. Please report issues at the GitHub issue tracker. Include your player YAML, the AP .zip output, your .apsave file, and a screenshot if possible.

How do I configure my options?

This world isn't part of the main Archipelago distribution yet, so it has no online player-options page. After installing the .apworld, create your config from the Archipelago Launcher instead:

Options Creator — a GUI that lists every option for each installed game (Kerbal Space Program 1 included), lets you set them visually, and exports a ready-to-use YAML.
Generate Template Options — writes a fully-commented template YAML for every installed game to your Players/Templates/ folder; open Kerbal Space Program 1.yaml, edit it, and use it as your config.

See the setup guide for step-by-step instructions.

Every option has a sensible default, so you only need to write down the ones you want to change. A config that tunes the goal and the filler pool looks like this:

name: YourName
game: Kerbal Space Program 1

Kerbal Space Program 1:
  goal: duna_return
  starting_body: kerbin
  difficulty: normal

  # Traps, buffs and science packs share one filler pool: turning either up
  # means fewer science packs.
  trap_density: light
  buff_density: normal

  # A MAPPING. Any key you leave out is weight 0, so this disables every trap
  # except the three listed.
  trap_type_weights:
    throttle: 1
    timewarp: 1
    comms_outage: 2      # twice as likely as the other two

  # A LIST. Writing it out REPLACES the default (all of them), so this enables
  # only these three and switches the other four off.
  buff_types:
    - isp
    - thrust
    - refuel

Those last two comments are the easiest thing to get wrong, and they behave differently:

Mapping options (trap_type_weights, contract_type_weights) treat an absent key as 0. Listing one trap does not "add" it to the defaults — it disables the other ten.
List options (buff_types, enabled_part_packs, the custom-goal body lists) replace the default set outright. If you list buff_types at all, anything you omit is off — including refuel, which is easy to forget because it is the only consumable.

If you just want everything on, leave the option out entirely rather than writing out the full set.

What does randomization do to this game?

Rocket parts (engines, fuel tanks, capsules, decouplers, etc.) are removed from the normal tech tree and shuffled into the multiworld item pool. You start with almost nothing and must receive parts from the pool to build increasingly capable rockets. The game must be played in Career Mode.

Instead of the stock science-experiment progression, your location checks are mission milestones: first launch, altitude records, orbits, landings, crew landings, flag plants, sample returns, and more across all 17 bodies in the Kerbol system. Completing a harder mission awards multiple checks at once (e.g., a Mun Sample Return also counts as a Mun Landing, Crewed Landing, etc.).

You also play contracts: native KSP contracts (orbit a body, rescue a stranded Kerbal, gather science and bring it home or transmit it, fly by a body and return, orbit a body and return, plant a flag, and more) injected into your game as items. Accepting and completing a contract checks its reward location, and under the default goal mode, completing contracts is what unlocks your victory condition. The orbital and rescue contracts are randomized — each seed hands you different target orbits to fly.

By default, most of the solar system also starts hidden. Bodies beyond your home neighbourhood are invisible (or unlabelled and un-clickable) and award no checks until they're discovered — normally by receiving their Discover item, though by default you can also reveal one by flying there (out of logic). Exploring the Kerbol system is itself part of your progression. See Hidden bodies below.

The tech tree is still present but restructured. Tech tree nodes are additional locations that cost science points to purchase. Science packs (filler items) provide science needed to buy them but you are still expected to gain science from your regular missions as normal.

What items and locations get shuffled?

Items

Parts are the core progression items. Every rocket part — engines, fuel tanks, capsules, probe cores, decouplers, solar panels, relays, heat shields, and so on — is its own individual item shuffled into the multiworld pool. You start with almost nothing and grow your parts catalogue as items arrive. A part is usable in the VAB/SPH the moment you receive it; generation simply never places a part in a location you couldn't reach yet, so you are never handed something you can't use.

Progressive items are the handful of non-part gates that still advance in tiers:

Progressive Item	What It Does
Progressive R&D (×5)	Unlocks successively higher bands of the tech tree, and (with Buildings In Logic) raises the R&D facility's science-cost cap so you can afford pricier nodes.
Progressive Science Instrument (×3)	Advances your science-instrument tier (it feeds the science-point budget).
Progressive Astronaut Complex (×2, buildings)	Unlocks EVA — flag planting, EVA in orbit, rescues, and surface samples away from home. Present when Buildings In Logic is on (default).
Progressive Tracking Station (×2, buildings)	Extends Deep Space Network range and unlocks patched conics. Present when Buildings In Logic is on (default).
Progressive Mission Control (×1, buildings)	Unlocks maneuver nodes for planning transfers and rendezvous. Present when Buildings In Logic is on (default).
Progressive Launch Pad (×3, optional)	Raises the launch-pad mass limit so you can fly heavier rockets. Present only if you enable the Progressive Launch Pad option.

Science Packs are filler items that grant science points, used to purchase tech tree nodes.

Contract items — one per contract in your seed. Receiving a contract item makes that native KSP contract available to accept; completing it checks its reward location(s).

Discover items — one Discover <Body> item per hidden body in your seed (present only when Body Visibility Mode hides bodies). Receiving one reveals that body and unlocks its missions, contracts, and science. They are always progression and can be placed anywhere in the multiworld, including another player's world. See Hidden bodies below.

Other equipment includes RTGs, batteries, docking ports, landing legs, ladders, reaction wheels, RCS, science instruments, and more.

Traps replace part of the filler pool when Trap Density is above none (default: light, ~10% of filler). A trap fires some time after you receive it, one at a time, and never twice — reverting a save cannot bring a suffered trap back. Most traps need you in flight (Time Slip can also strike at the Space Center or Tracking Station), and timed trap effects run in real time: time warp does not shorten them. Traps never appear in the starting inventory. Which traps appear is controlled by Trap Type Weights (all equally likely by default; weight 0 disables one):

Stage Fright — a 15-second fuse (warning at ten, hard count from five), then your next stage fires. No cancel — but a stage lock (Alt+L) engaged at zero wins.
Gravity Storm — local gravity runs 20–50% off for a while.
Spin Cycle — the craft is thrown into a random tumble.
Radio Silence — every antenna goes dead for a while.
Short Circuit — electric charge drains rapidly for a few seconds.
Thermal Runaway — one part heats toward (but not past) its failure point.
Loose Bolts — one peripheral part falls off. Permanently.
Mandatory Spacewalk — a kerbal decides to step outside. Right now.
Time Slip — time warp changes on its own.
Sticky Throttle — the throttle jumps to a random setting.
Minor Kraken Attack — solar panels, gear, and antennas all toggle. Yes, in atmosphere too.

Buffs are the upside twin of traps, and also come out of the filler pool (so a higher Buff Density means fewer science packs). Most of them are permanent: they apply for the rest of the run the moment you receive them, and copies stack additively — three Engine Efficiency I is +3%, not +3.03%. Every permanent type ships as a three-rung ladder: I is +1%, II is +3%, III is +5%. At the default normal density you get 3× I, 2× II and 1× III of each enabled type, so a single type can reach +14%; light caps it at +4% and heavy at +24%. Structural Integrity runs a steeper 5 / 15 / 25 ladder (so a +70% ceiling at normal) — the stats it scales are small enough in absolute terms that the standard rungs would be imperceptible. Unlike traps, buffs are allowed in the starting inventory. Which types appear is controlled by Buff Types.

Engine Efficiency — engines burn fuel more efficiently. Thrust is unchanged; you just get more Δv.
Engine Thrust — liquid engines push harder for better TWR. Solid boosters are deliberately excluded: they cannot be throttled down, so buffing them would make ascents harder to fly, not easier.
Heat Tolerance — every part survives a higher temperature.
Structural Integrity — parts survive harder impacts, more joint stress, higher g, and greater pressure (crush depth).
Control Authority — stronger reaction wheels and wider engine gimbal range.
Power Generation — solar panels, RTGs, and fuel cells all produce more electric charge. Worth most in the outer system, where solar output has fallen off with distance.

The rest are consumables: instead of applying themselves, each copy you receive banks one charge you spend from the AP mod menu at the moment you want it. Buff Density sets how many charges of each enabled consumable you get across the run — 1 at light, 3 at normal, 5 at heavy.

Mid-Air Refuel — refills the fuel tanks on the craft you are currently flying, wherever it is. It tops up fuel only: ore and other ISRU resources are untouched. Spending a charge consumes it once and for all — reverting the save does not hand it back, so bank it for a flight you would otherwise have to abandon.

Buffs are invisible to the randomizer's logic — permanent and consumable alike. A buff can never make an out-of-logic mission reachable; it only makes a mission you could already fly easier to fly. Nothing in the logic ever assumes you saved a charge.

Locations

Locations are mission-based (plus contracts), not science-experiment-based. You don't run individual experiments; instead you complete missions and contracts:

Starting Inventory (5–20 slots depending on difficulty) — Zero-requirement locations that bootstrap your run. The AP fill algorithm places the items you need to get started here.
KSC Biome Checks (12) — Earned by performing science experiments at KSC buildings (Launch Pad, VAB, R&D, Tracking Station, etc.). Each is named Science from KSC to make the requirement obvious. Only one per building, not each sub-building biome.
Home-body Milestones (11) — First Launch, First Landing, First Crash, altitude records, First Staging. Plus a single body-agnostic Splashdown check that fires on any ocean body (Kerbin / Eve / Laythe).
Body Mission Events (~300) — Per-body checks across all 17 bodies: Flyby, Orbit, Landing, Crewed Landing, Flag Plant, Sample Return, and three separate return tiers — SOI Return (fly by and come home), Orbit Return (capture into orbit and come home) and Return (land and come home). Each event type has multiple slots. The three return tiers are independent: a direct-entry landing awards SOI Return and Return but not Orbit Return, because that craft never orbited.
Tech Tree Nodes (124–248) — Each of the 62 tech nodes has 2–4 location slots (scaled by difficulty). Purchasing a node with science points awards these checks.
Contracts (10 by default) — Native KSP contracts injected by the client; completing one checks its reward location(s). Under the default Count goal mode, completing contracts is also how you unlock your goal.

KSC building upgrades (Buildings In Logic)

With Buildings In Logic (on by default) your KSC facilities start un-upgraded and you unlock them by collecting progressive items — they are no longer free from the start. Each facility gates a different capability:

Astronaut Complex — EVA actions. Planting a flag and doing an EVA in orbit require the upgrade (even on your own home body), as do rescues and reaching a Kerbal outside the craft on any body other than home.
Tracking Station — Deep Space Network range (a weaker station needs a stronger antenna, so distant uncrewed missions and far science transmission require upgrading it) and patched conics.
Mission Control — maneuver nodes, which (together with conics) let you plan transfers and rendezvous.
Research & Development — surface samples (a Kerbal collecting surface material needs the R&D facility, even at home) and the science-cost cap described below.

Turn Buildings In Logic off to play with every facility maxed from the start (closer to a science-sandbox feel), where no building gates anything.

Progressive R&D: tech bands and the R&D building (this is not a bug)

Progressive R&D does double duty, which surprises people — it is working as intended:

Every Progressive R&D copy unlocks the next band of the tech tree — i.e. which nodes you are allowed to buy. You get 5 total, and the early bands are deliberately generous (your first copy opens several early tiers).
Two of those copies — the 2nd and the 4th — also upgrade the R&D building itself. The building level sets KSP's science-cost cap: the price of the most expensive node you may purchase (100 → 500 → unlimited science). The 2nd copy raises the building to the middle level (and unlocks surface samples); the 4th raises it to max.

So most Progressive R&D items only open new tech, but two of them also bump the R&D building. That is deliberate: the building upgrades are placed so the science-cost cap is never the thing blocking you — the tech band you've unlocked is always the real limit. If you receive an R&D item and the building does not visibly upgrade, that is expected — only the 2nd and 4th copies do.

Hidden bodies (Body Visibility Mode)

By default some celestial bodies start hidden — invisible or unlabelled on the map, off the Tab-cycle, and unable to award any location checks — until you receive their Discover <Body> item. This turns the Kerbol system itself into progression: you unlock where you can go, not just what you can fly.

Body Visibility Mode decides which bodies start hidden:

auto (default) — chosen from your goal. A goal confined to your home system hides even the home system (like home_only), so you discover your own neighbourhood one body at a time; any wider goal hides everything outside your home system (like home_system).
all_visible — feature off. Every body is visible from the start, exactly as before, and no Discover items are added.
home_system — your home body and the rest of its local system are visible; every other body is hidden until discovered.
home_only — only your home body is visible; everything else, including the rest of your home system, is hidden until discovered.

Your home body and the Sun are never hidden. Planets are always discovered before their moons — a moon's Discover item only becomes reachable once you hold its planet's.

While a body is hidden it awards no location checks — its flybys, orbits, landings, samples, and contracts are dormant until it's revealed. There are two ways to reveal one: receiving its Discover item (the in-logic route, which also restores its map label, targeting, and science), or — when Allow Undiscovered Bodies is on — simply flying there and entering its SOI. Once revealed by either route, its checks fire normally; a fly-there reveal just isn't something the seed's logic ever relies on.

Allow Undiscovered Bodies controls whether you can physically reach a body you haven't discovered:

On (default) — a hidden body's sphere still exists but is uninteractable: no map label, not clickable, not Tab-selectable. You can fly a probe there anyway — this is out of logic, AP never requires it — and entering its SOI reveals the body locally, at which point its flyby (and every later) check fires normally. That fly-there reveal is remembered across restarts.
Off — a hidden body is fully invisible; its sphere is removed from the game. Flying into its SOI destroys your craft ("collided with undiscovered body") before any check can fire — so with this setting the Discover item is the only way to unlock a body's checks. This is intended, not a bug: you flew into a body you couldn't see.

Either way, the seed's logic only ever requires a body's Discover item to unlock it. The auto default means most players never touch these options — the mode is picked from your goal, and every body you actually need is gated behind a Discover item the fill algorithm guarantees you can reach.

Tech-tree interaction (not a bug): an undiscovered body's science does not count toward your science budget until you discover it. A science-hungry tech tier can therefore stay unaffordable until you have discovered enough of the system — discovering bodies is part of how you afford the deeper tree. This is why the Complete Tech Tree goal remains solvable with hidden bodies enabled.

Which items can be in another player's world?

Any KSP item can appear in another player's world — individual parts, the progressive items (R&D, Science Instrument, Launch Pad), science packs, contract items, and Discover items can all be placed in other games' locations.

What does another world's item look like in KSP?

Items for other players appear as mission checks and tech tree purchases. When you complete a mission or buy a tech node, any items at those locations are sent to their respective players.

When the player receives an item, what happens?

When you receive a part, it becomes available in the VAB/SPH for building rockets immediately — there is no tier to unlock first. Science packs are added to your science balance right away, and receiving a contract item makes that contract available to accept.

What is the victory condition?

The victory condition is configurable. Preset goals include:

Duna Return (default) — Return a vessel or crew from Duna.
Eeloo Return — Return from Eeloo.
Flag Every Body — Plant a flag on all 15 landable bodies.
Standard Returns — Return from 11 bodies (excluding Eve, Tylo, Laythe).
Standard Sample Returns — Crewed sample return from the same 11 bodies.
Complete Tech Tree — Purchase all 62 tech tree nodes.
Mun Flag — Plant a flag on the Mun (short run).
Mun Sample Return — Crewed sample return from the Mun (short run).
Jool Moons Return — Return from each Jool moon (Laythe, Vall, Tylo, Bop, Pol). Your home body is filtered out, so a Laythe start gives a tight 4-target Jool-system goal.
Random Contracts — No destination goal: complete a number of your available contracts, then plant a flag at home to win. Only valid with Goal Contract Mode = count or progressive_unlock.
Custom — Build your own goal from five body-list options: flag_bodies, return_bodies, sample_return_bodies, orbit_bodies, and flyby_bodies. Set goal to custom and populate one or more of these lists with body names. orbit_bodies and flyby_bodies accept all 17 bodies including Jool and Kerbol; the others only accept landable bodies.

Short run goals: When all goal bodies are in the Kerbin system (Kerbin, Mun, Minmus), progression items are automatically restricted from appearing at interplanetary locations. You will never be forced to fly to Duna or beyond to complete a Mun-only goal. Interplanetary missions are still available as optional content — they just won't contain items required for progression.

Key options

Difficulty — Controls delta-V margins, starting location count, and tech tree density. Casual is forgiving; Expert assumes near-optimal delta-V piloting. Only Normal has been thoroughly tested so far.
Buildings In Logic — On by default. Gates the Astronaut Complex, Tracking Station, Mission Control, and R&D facility as progression, so you unlock EVA, comms/conics, maneuver nodes, and the tech science-cost cap by collecting the matching Progressive items (see KSC building upgrades above). Turn it off to start with every facility maxed.
Enabled Part Packs — Which optional DLC part packs to include. The Making History pack is enabled by default, so the seed uses its parts — if you do not own the Making History DLC you must opt out by removing MakingHistory from this set, or you'll be handed parts you can't build. Stock parts are always available regardless.
Goal Contract Mode — How your goal is unlocked. Count (default): complete a number of your available contracts and the goal is awarded. Other modes: Findable (the goal item is in the multiworld pool and found like any other item), Starting (the goal is granted up front, limited only by physics/parts), and Progressive Unlock (goal missions unlock one at a time as you complete contracts).
Contracts Available — How many ordinary (non-goal) contracts are placed in the seed (default 10). These are side objectives the client tracks; completing them is how Count and Progressive Unlock release your goal. Contract mission types and their relative frequency are configurable too.
Exclude Late Tech Tree — Prevents progression items from being placed in tier-8 tech nodes, avoiding a late-game science grind if you'd rather focus on flying missions than gaining science.
Start With Launch Clamps — Enabled by default. Disabling makes launch clamps a progression gate for interplanetary missions. It is important to note that you might not get any landing legs so disabling this may be seed breaking.
Body Visibility Mode — Which celestial bodies start hidden, revealed by Discover items. Default auto, which picks a sensible mode from your goal (see Hidden bodies above). Set to all_visible to turn the feature off entirely; home_system / home_only force a specific scope.
Allow Undiscovered Bodies — On by default. On: undiscovered bodies are visible-but-uninteractable and can be flown to out of logic (arriving reveals them). Off: they are invisible and flying into their SOI destroys your craft. Only meaningful when Body Visibility Mode is hiding bodies.

Filler pool options

Science packs, traps and buffs all come out of the same filler pool, so turning traps or buffs up means fewer science packs. None of them affect logic — a trap can never make a check unreachable, and a buff can never make an unreachable check reachable.

Trap Density — How much of the filler pool becomes traps. none, light (default, ~10% of filler), moderate (~25%), heavy (~50%), hell (every filler item is a trap). See Traps above for what each one does.
Trap Type Weights — Relative weight of each trap type in the trap pool; weight 0 disables that trap entirely. All eleven are enabled and equally likely by default. Note this is a mapping, and any key you leave out counts as 0 — see the example above.
Buff Density — How many buff items are added. none, light, normal (default), heavy. This sets both how many you find and how high one type can stack: +4% / +14% / +24% for the standard ladder, or +20% / +70% / +120% for Structural Integrity's steeper one. It also sets how many Mid-Air Refuel charges you get: 0 / 1 / 3 / 5 per run.
Buff Types — Which buff categories appear (isp, thrust, heat_tolerance, structural, control, power, and the consumable refuel). All are enabled by default. This is a list, and writing it out replaces the default — any name you omit is switched off.
Death Link — Off by default. When on, losing a Kerbal or losing the craft you are flying broadcasts a death to everyone else on DeathLink, and their deaths destroy your craft. Losing the craft means the game itself counts the vessel as destroyed (its root part is gone) — shedding a landing leg, a solar panel, or a spent booster on impact does not count, so you can still lithobrake. Practice flights (the mod's simulation mode) neither send nor receive deaths.
Death Link On Revert — Off by default. Requires Death Link. Also broadcasts a death when you Revert a flight, so a failure can't be save-scummed away for free. Reverting a craft that never actually launched — still clamped on the pad, or on the runway before you taxi — is always free, and a flight that already broadcast a death never sends a second one when you revert it.

Tracking In-Logic Locations

KSP1 integrates with the Universal Tracker (UT), a general-purpose tracker that works across all AP games. No YAML file is needed — UT reconstructs the full logic state from slot data when you connect.

UT connects to the AP server and shows you which unchecked locations are currently in logic, grouped by body (Kerbin system first, then interplanetary bodies, then tech tree and KSC). It updates automatically as you receive items and complete checks.

KSP-specific features via UT:

/explain <location> — Shows a detailed rocket design for any location: which engines, tanks, and equipment logic thinks you need, and why a mission might not be in logic yet.
/explain parts [filter] — Lists all parts you've received, grouped by type. Optionally filter by name (e.g. /explain parts engine).

I am stuck!

Use UT's /explain command to see exactly what the logic engine thinks you need for a mission and why it might not be reachable yet. This is the fastest way to understand what's blocking you.

If you believe a location shown as in-logic is not actually achievable with your current parts, please file an issue with the location name and either your parts list (from /explain parts) or your .zip and .apsave files.

Credits

The in-game flags shipped with the client mod are based on the wonderful work of 1Kerbonaut from the KSP-Style-Flags project (v1.0). Many thanks for making them available!