Known File Extensions
From RuneWiki
Data
.base: "Animation template file"
.ob3: "Jagex model file"
.ob2: legacy model file format
.jgd: "JGD text file" Jaged (Jagex editor) model
.anim: Animation frames
.jm2: Map
.synth: Sound effects
Configs
.area
.constant / .macro
.cs2: ClientScript
.enum: Enumerations
.flo: Floor overlay
.flu: Floor underlay
.headbar
.hitmark
.hunt: Hunt mode
.idk: Identity kit
.inv: Inventory
.loc: Location
.npc: Npc
.obj: Object
.param: Parameters
.rs2: RuneScript
.seq: Sequence
.spotanim: Spot animation
.varp: Player variables
.varbit: Player bit variables
.varn: Npc variables
.varnbit: Npc bit variables
.vars: Shared (world) variables
.varsbit: Shared (world) bit variables
.varobj: Object variables