Screeps Articles and Debugging Guides

Movement and VisionIntermediateGuide

Screeps: Why Game.rooms[roomName] Is Undefined

Learn why Game.rooms[roomName] is undefined without current room vision, how to guard live Room reads, and why Memory.rooms does not prove visibility.

13 min read

Rooms Debugging

Movement and VisionIntermediateGuide

Screeps Creep.pull(): Coordinate Two Creeps in One Tick

Coordinate Creep.pull(), the puller's movement, and target.move(puller) in the same tick, handle adjacency and fatigue correctly, and verify the pair moved later.

13 min read

Movement Creeps Debugging

Movement and VisionIntermediateGuide

Screeps PathFinder.search(): Goal Range, Complete Paths, and the incomplete Flag

Call PathFinder.search() with the goal range your action actually needs, interpret path, ops, cost, and incomplete correctly, and reject partial paths before handing movement to a Creep.

15 min read

Movement Pathfinding

Movement and VisionIntermediateDebugging

Screeps moveTo() Returns OK but the Creep Stays Put

Verify movement over later ticks, then isolate fatigue, repeated movement intents, traffic, cached paths, room edges, and impossible stop ranges.

13 min read

Movement Debugging Pathfinding

Movement and VisionIntermediateGuide

Screeps CostMatrix 255: Why It Means Unwalkable

In Screeps PathFinder, a CostMatrix cost of 255 is unwalkable. See what 0, 1–254, and 255 mean, plus practical road, obstacle, and roomCallback rules.

13 min read

Pathfinding Movement

Movement and VisionIntermediateDebugging

Screeps ERR_NO_PATH: Diagnose Range, Matrices, and Routes

Separate ERR_NO_PATH from missing cached paths and incomplete PathFinder searches, then inspect goal range, CostMatrix rules, callbacks, limits, and room routes.

15 min read

Movement Pathfinding Debugging

Movement and VisionIntermediateDebugging

Screeps ERR_NOT_IN_RANGE: Use the Correct Action Range

Find the action that returned ERR_NOT_IN_RANGE, use its documented range, submit movement separately, and retry the action on a later tick.

11 min read

Movement Debugging

Movement and VisionIntermediateGuide

Screeps Game.map.findRoute(): Plan and Execute One Room Step

Separate room planning from exit-tile pathfinding, validate the first route step, use finite risk costs versus hard bans, and verify the border transition on later ticks.

14 min read

Movement Pathfinding Rooms

Movement and VisionAdvancedGuide

Screeps Observer: Coordinate One Final observeRoom() Call

Collect requests, choose one target per Observer, make one final observeRoom() call, store only that accepted target, read it next tick, and keep visibility attribution honest.

13 min read

Rooms Debugging

Movement and VisionIntermediateGuide

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.

16 min read

Movement Creeps

Movement and VisionIntermediateGuide

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.

15 min read

Movement Pathfinding

Publication standard

English articles are published only after source review, official API checks where applicable, JavaScript syntax review where code is present, duplicate-intent and link checks, and editorial review. Publication does not imply Console or multi-tick live-room verification; those evidence states remain separate in each guide. Review the verification method.