ERROR REFERENCE
Return codes
Use common Screeps return codes as the first branch in an action debugging process.
Open error codes →SCREEPS KNOWLEDGE BASE
Browse Screeps by system
Browse 64 published English guides through eight indexable system pillars. Newly published guides appear in the relevant system automatically.
01
Memory and Code Structure
State, modules, global cache, RawMemory, flags, and maintainable game-loop structure.
10 published guides · Open system page- GETTING STARTED · BEGINNER LESSON 1 OF 12What Is Screeps? A Programming Strategy Game8 min read · Beginner · Lesson
- GETTING STARTED · BEGINNER LESSON 3 OF 12Screeps Ticks and Game Loop: Why Your Code Runs Repeatedly8 min read · Beginner · Lesson
- FOUNDATION · MEMORYHow Screeps Memory Saves Creep Roles and Working State12 min read · Intermediate · Guide
- FOUNDATION · WORKING STATEHow to Switch a Screeps Creep Between Getting Energy and Working15 min read · Intermediate · Guide
- FOUNDATION · TARGET RESTORATIONHow to Restore a Screeps Target from Memory with Game.getObjectById()16 min read · Intermediate · Guide
- FOUNDATION · MEMORY CLEANUPHow to Clean Dead Creep Memory Safely in Screeps14 min read · Intermediate · Guide
02
Spawn and Creep Lifecycle
Body design, spawn return codes, role memory, renewal, recycling, and emergency recovery.
8 published guides · Open system page- GETTING STARTED · BEGINNER LESSON 6 OF 12Screeps Creep Body Parts: WORK, CARRY, and MOVE8 min read · Beginner · Lesson
- GETTING STARTED · BEGINNER LESSON 7 OF 12Screeps spawnCreep(): Create Your First Creep8 min read · Beginner · Lesson
- GETTING STARTED · BEGINNER LESSON 8 OF 12Screeps Creep Roles: Harvester, Upgrader, and Builder8 min read · Beginner · Lesson
- SPAWNING · RETURN-CODE DEBUGGINGHow to Debug spawnCreep() Return Codes in Screeps16 min read · Intermediate · Debugging
- SPAWNING · DYNAMIC BODY DESIGNHow to Build a Screeps Creep Body from Available Energy15 min read · Intermediate · Guide
- SPAWNING · EMERGENCY RECOVERYHow to Recover a Screeps Room with No Harvesters16 min read · Intermediate · Guide
03
Room Economy
Harvesting, hauling, storage, links, terminals, minerals, and stable energy flow.
7 published guides · Open system page- GETTING STARTED · BEGINNER LESSON 4 OF 12Screeps Harvest Energy: Your First Creep Script9 min read · Beginner · Lesson
- GETTING STARTED · BEGINNER LESSON 5 OF 12Screeps Energy Delivery: Creep to Spawn10 min read · Beginner · Lesson
- FOUNDATION · CONTAINER WITHDRAWALHow to Make a Screeps Creep Withdraw Energy from a Container11 min read · Intermediate · Guide
- RESOURCE RECOVERY · DROPPED ENERGYHow to Make a Screeps Creep Pick Up Dropped Energy14 min read · Intermediate · Guide
- LOGISTICS · STORAGE ENERGY RESERVEHow to Use Storage Energy Without Draining Your Reserve18 min read · Intermediate · Guide
- LOGISTICS · LINK ENERGY NETWORKHow to Transfer Link Energy Without Depending on Structure Array Order18 min read · Intermediate · Guide
04
Movement and Vision
moveTo(), fatigue, RoomPosition, PathFinder, routes, observers, and room visibility.
10 published guides · Open system page- GETTING STARTED · BEGINNER LESSON 2 OF 12Screeps First Room: Find the Editor and Console8 min read · Beginner · Lesson
- MOVEMENT · ACTION RANGE DEBUGGINGHow to Fix ERR_NOT_IN_RANGE in Screeps15 min read · Intermediate · Debugging
- MOVEMENT · NO-PROGRESS DEBUGGINGWhy moveTo() Returns OK but Your Screeps Creep Does Not Move16 min read · Intermediate · Debugging
- MOVEMENT · PATHFINDING DEBUGGINGHow to Debug ERR_NO_PATH in Screeps18 min read · Intermediate · Debugging
- MOVEMENT · FATIGUE AND BODY DESIGNHow to Calculate Screeps Creep Movement Speed16 min read · Intermediate · Guide
- MOVEMENT · ROOMPOSITION DISTANCEWhich Screeps RoomPosition Distance Method Should You Use?15 min read · Intermediate · Guide
05
Controllers and Expansion
Upgrading, downgrade recovery, reserving, claiming, safe mode, and remote control.
4 published guides · Open system page- GETTING STARTED · BEGINNER LESSON 9 OF 12Screeps upgradeController(): Build Your First Upgrader Loop10 min read · Beginner · Lesson
- CONTROLLER · SAFE MODE ACTIVATIONHow to Activate Safe Mode Without Accidental Repeated Use18 min read · Advanced · Debugging
- CONTROLLER · DOWNGRADE RECOVERYHow to Detect Controller Downgrade Risk and Recover Safely18 min read · Intermediate · Guide
- CONTROLLER · RESERVE OR CLAIMHow to Choose Between Reserving and Claiming a Controller19 min read · Intermediate · Guide
06
Construction and Defense
Construction sites, towers, walls, ramparts, repairs, and defensive priorities.
12 published guides · Open system page- BEGINNER · FIRST EXTENSIONHow to Build Your First Screeps Extension12 min read · Beginner · Lesson
- BEGINNER · BUILD AND REPAIRHow to Make a Screeps Creep Build and Repair Automatically14 min read · Beginner · Lesson
- API SAFETY · CONSTRUCTIONHow to Remove a Construction Site Safely in Screeps12 min read · Intermediate · Safety
- DEFENSE · TOWER ATTACK PRIORITYHow to Make Towers Attack Hostiles with Explainable Priorities18 min read · Intermediate · Guide
- DEFENSE · TOWER HEAL PRIORITYHow to Make Towers Heal the Creep That Needs It Most17 min read · Intermediate · Guide
- DEFENSE · TOWER REPAIR RESERVEHow to Repair Structures with Towers Without Spending Defense Energy18 min read · Intermediate · Guide
07
Market and Advanced Resources
Orders, deals, terminals, labs, boosts, factories, power, and late-game resources.
8 published guides · Open system page- MARKET · SAFE ORDER CREATIONHow to Create a Market Order Safely in Screeps18 min read · Advanced · Guide
- MARKET · REVIEWED ONE-TIME DEALHow to Execute a Reviewed Market Deal Safely19 min read · Advanced · Guide
- LOGISTICS · DIRECT TERMINAL TRANSFERHow to Send Resources Between Terminals Safely18 min read · Advanced · Guide
- RESOURCES · LAB REACTION WORKFLOWHow to Run Lab Reactions Safely in Screeps18 min read · Advanced · Guide
- RESOURCES · LAB BOOST WORKFLOWHow to Boost Creep Body Parts Safely in Screeps18 min read · Advanced · Guide
- RESOURCES · FACTORY PRODUCTION WORKFLOWHow to Produce Factory Commodities Safely in Screeps19 min read · Advanced · Guide
08
Operations and Debugging
Return codes, CPU, bucket, event logs, notifications, diagnostics, and safe operations.
5 published guides · Open system page- BEGINNER · FIRST ROOM LOOPHow to Combine Your First Screeps Room Loop20 min read · Beginner · Lesson
- RUNTIME · CPU MEASUREMENT AND BUDGETINGHow to Measure and Control CPU Usage in Screeps17 min read · Intermediate · Guide
- OBSERVABILITY · RATE-LIMITED ALERTSHow to Send Reliable Alerts with Game.notify()17 min read · Intermediate · Guide
- OBSERVABILITY · PREVIOUS-TICK EVENT LOGSHow to Read Room.getEventLog() Safely in Screeps18 min read · Intermediate · Guide
- OBSERVABILITY · ROOMVISUAL DEBUG LAYERHow to Build a Safe RoomVisual Debug Layer in Screeps18 min read · Intermediate · Debugging
GLOSSARY
Core terminology
Review concise definitions for the objects, resources, limits, and runtime concepts used across Screeps.
Open the glossary →TOOLS
Calculate and diagnose before editing production code
The current English tool set includes a Creep body calculator and a room snapshot diagnostic tool.
Browse tools →