The book is a repository of information about level design within 3D games. It can be read at https://book.leveldesignbook.com/ and is licenced under the Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International (CC BY-NC-SA 4.0), which you can read at https://creativecommons.org/licenses/by-nc-sa/4.0/.
https://book.leveldesignbook.com/introduction
Level design focuses on player behaviour, whereas environment artists focus on the graphics.
Good environment art supports experience design goals and helps players.
Room design vs. world design: you can pore over details in a single room, but is impractical where there may be hundreds (even thousands) of rooms.
World design: flow and wayfinding of neighbourhoods instead of houses—macro level view instead of micro.
An urban planner approach.
"The only way to become a level designer... is to make levels. Ideally, a lot of levels."
the general player movement through the level.
Feel, sensation, ease of movement
Critical path/golden path: minimum path to complete level and progress. Ignores optional areas, highlights the critical parts of the level
Convey the ideal design goals and requirements, not reality
Represent functional logic and design intent, communicates what is important about it.
Circulation: areas that connect other areas
Hallways, aisles and stairs
Generally a bigger/wider passage feels like primary public, while narrow areas feel secondary.
Diegetic circulation or formal circulation: What looks/feels like circulation vs what functions like it.
Gone Home: old mansion theme, hub and spoke typology to tell a story
Formal is about physical function + affordance for movement, less emphasis on history and cultural context. How does an expert/speedrunner understand the map?
TF2 Payload maps are single lane: one push, one defend
3 lane like in CoD and Counter-Strike, bidirectional critical paths that branch andor intersect with smaller lanes
Verticality: Vertical flow, how it feels to move up/down
Descent into a dungeon, scaling a cliff
Desire path: routes indicating the most efficient path even if it isn't official
Central idea/concept of a project
Central core idea that anchors the rest of the design
Layouts that promote certain behaviours
Abstraction of layouts, help simplify the layout.
Cover: Half, full vs hard/soft
Gates: Block player progress until they get an ability, otherwise the player can leave
Generalised layout patterns for a chunk of the level
Generalised layout patterns for multiple rooms/entire levels
There are also multiplayer layouts as multiplayer games tend to be non-linear, circuitous and bidirectional.