Space & Locomotion
Twenty-three ideas about where the player is permitted to be, running from a single frame of Pong to a planet you can descend to without a loading screen.
Every entry in this family answers one question: what shape is the space, and what must the player do to cross it. Object Collision As Verb in Spacewar! (1962) is the root of the family and of most of the graph — two things overlap and something happens. Pong compresses that into a Single-Screen Arena, and for most of a decade the frame is the world. Defender breaks the frame in 1980 by decoupling the camera from the playfield, which is the precondition for everything larger than a screen: Super Mario Bros.'s Momentum-Based Platform Control, Metroid's Ability-Gated Interlocked Map, and eventually Grand Theft Auto III's Seamless Streaming Open World, which converts levels into places.
Depth arrives twice. First as a lie — Moon Patrol's parallax layers, Zaxxon's isometric grid, Pole Position's scaling sprites, F-Zero's rotating ground plane — and then as real geometry, in Wolfenstein 3D's raycast corridors and Quake's rooms stacked above rooms. Super Mario 64 supplies the third-person grammar that nearly every 3D action game still runs on.
Designers keep re-litigating one question here: how much of the route belongs to them. Metroid locks space behind capabilities. Assassin's Creed annotates architecture as a climbing grid and calls the result a city. Mirror's Edge makes traversal the primary verb while painting the intended line onto the world. Breath of the Wild deletes the annotation and lets a stamina bar be the only limit. Portal takes the extreme position and hands topology itself to the player. Nobody has settled whether an authored route or an unbounded one makes a world feel larger.
The family, in order of arrival
Every mechanic in this family
Inherited from other families
Mechanics outside this family that parent something inside it — where the cross-pollination happens.