How to Fix ERR_NOT_IN_RANGE in Screeps
Identify which action returned ERR_NOT_IN_RANGE, use its real range, save the moveTo() result separately, and retry the original action on a later tick instead of assuming movement is immediate.
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Practical Screeps articles for the problem you need to solve
Browse 64 published guides by system, difficulty, content type, or topic. Start with What Is Screeps? A Programming Strategy Game or follow the beginner sequence through How to Combine Your First Screeps Room Loop.
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Why moveTo() Returns OK but Your Screeps Creep Does Not Move
Distinguish an accepted movement order from later position change, validate the target and active MOVE parts, inspect fatigue and range, track roomName:x:y across ticks, and diagnose traffic, cached paths, and overwritten movement orders.
How to Debug ERR_NO_PATH in Screeps
Distinguish ERR_NO_PATH, ERR_NOT_FOUND and PathFinder incomplete results; validate target range; correct CostMatrix walkability; inspect callbacks, maxOps, maxRooms and cross-room routes; and separate temporary traffic from a failed search.
How to Calculate Screeps Creep Movement Speed
Calculate unboosted Creep movement from MOVE recovery, loaded body weight, road, plain, and swamp costs; account for empty CARRY parts; and separate a static body estimate from live multi-tick movement proof.
Which Screeps RoomPosition Distance Method Should You Use?
Choose between getRangeTo(), inRangeTo(), isNearTo(), isEqualTo(), findClosestByRange(), findClosestByPath(), and findInRange() without confusing linear range with route reachability.
How to Plan and Execute a Cross-Room Route in Screeps
Use Game.map.findRoute() as a room-level plan, assign routeCallback costs, reject rooms deliberately, validate the first exit step, rebuild after room transitions, and keep route preference separate from live safety intel.
Why Is Game.rooms[roomName] Undefined in Screeps?
Understand when a Room exists in Game.rooms, separate current-tick visibility from historical Memory, guard Controller and structure reads, and build a safe visibility-first inspection helper.
How to Use StructureObserver.observeRoom() Safely
Schedule Observer vision, store the accepted request, read the target Room on the next tick, preserve bounded intel, handle return codes, and avoid claiming that current visibility proves the new request completed.
How to Build a Safe PathFinder CostMatrix in Screeps
Use CostMatrix values 0–255 correctly, classify roads and structures, separate invisible rooms from blocked rooms, layer dynamic Creep costs, validate coordinates, and reject incomplete PathFinder results.
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English articles are published only after source review, official API checks where applicable, JavaScript syntax review where code is present, duplicate-intent checks, and a final score of at least 96.