Tone
Also said as Mood, Register
The attitude a work takes to its own events: grim, silly, cosy, cruel. The same facts can be told in any tone and produce a different game.
Everyone on the team makes tone decisions every day, in every line and texture, whether they know it or not. If nobody names it, the game wanders from one to the next and players feel it as cheapness.
Say it
“Fix the tone: dry and quietly funny, like someone who has seen worse. No puns during the funeral. Jokes come from people being stubborn, not from winking at the player.”
Where you’ve seen it
Fallout tells a story about nuclear ruin in the voice of a cheerful 1950s advert, with Vault Boy smiling and giving a thumbs up. The joke and the horror depend on each other, and the tone is the series' identity.
Not to be confused with genre
Genre is what kind of thing it is. Tone is how it feels about being that thing. Horror can be deadly serious or a comedy.