one dataset · paper, tables, graph, wiki
simgrammar the grammar of simulation

parts

7 mechanics, as Garry's Mod does them

core · 3

multiplayer & persistence

Modding API

A Lua API covers entities, weapons, HUD, and game rules; servers send addons to clients on join, and community game modes (TTT, Prop Hunt, DarkRP) became the main way people play.

space & construction

Modular assembly

The tool gun joins props with welds, ropes, axles, sliders, winches, motors, wheels, and thrusters, turning loose props into vehicles and machines.

physics & materials

Rigid-body physics

Every spawned prop and ragdoll is a physics object; the physics gun lifts, rotates, and freezes them, and collisions, gravity, and buoyancy follow the Source physics engine.

supporting · 4

control & automation

Blueprints

The duplicator tool and Advanced Duplicator addon copy and paste multi-prop contraptions.

multiplayer & persistence

Content sharing

Steam Workshop distributes saves, dupes, maps, and addons.

control & automation

Direct avatar control

The player is a first-person character who walks, flies with noclip, and wields the physics and tool guns.

control & automation

Signal circuits

The Wiremod addon adds wires, sensors, gates, and programmable chips to contraptions.

core loop

spawn props, ragdolls, and NPCs -> move and freeze them with the physics gun -> weld, rope, and motor them with the tool gun -> test the contraption or scene -> share it, or play a community game mode built on the same tools

design notes

Garry's Mod exposes the Source engine's rigid-body physics directly: the physics gun grabs, rotates, and freezes any prop, and the tool gun adds welds, ropes, axles, motors, thrusters, and other constraints, so contraptions are built from rigid bodies and joints. Its larger contribution is that the whole game is scriptable in Lua and servers download addons on join, so most play happens inside player-made game modes such as Trouble in Terrorist Town, Prop Hunt, and DarkRP, and the add-on Wiremod adds sensors and logic gates. Garry's Mod began as a free Half-Life 2 mod in 2004 and became a paid Steam product in 2006.

appears in

the paper, 2 sections · 2 chapters
paper

5. The structure of the design space

linked in this section of the paper

paper
paper

Appendix A. Game catalog

linked in this section of the paper

paper
catalog

The catalog

listed with its year, developer, subgenre, and number of mechanics

book
ch 1

Chapter 1. Same parts

linked from the text

book
ch 4

Chapter 4. Families

linked from the text

book

sources

1
Wikipedia contributors (2026). Garry's Mod. Wikipedia

provenance

runs in log/runs
2026-10-24
created2026-10-24-catalog-ggcatalog
2026-10-25
reviewed2026-10-25-store-ids-pilotcatalog