Player metrics
Also said as Metrics, Character metrics, Level metrics
The measurements of what the character can do: jump height, longest jump, run speed, how high a wall they can climb, how wide a door they fit through. Every level is built out of these numbers.
Decide them late or change them after levels exist and every gap in the game is wrong. Written down, they let you build a level before there is any art, and know it can be crossed.
Say it
“Freeze the metrics this week: jump 3 m high, 6 m long at a run, doors 2 m wide, cover 1.2 m tall. Every room we block out from now on uses these.”
Where you’ve seen it
Super Mario Bros. was planned on graph paper in a grid of blocks, so a designer can count a gap in blocks and know whether a running jump will clear it.
Not to be confused with analytics
Same word, different job. Player metrics here are the character's measurements. Analytics, also called metrics, are data about how people played.