Normally, my content lifespan document would take the form of a long table with a single row for each element in the game (it would include buildings, obstacles, playable and non-playable characters, interactive objects, cutscenes, weapons, abilities, scenery, level design, and so on). I'd then add columns that contained the following: a short description, the first time an element is used, priority, and dependency (an obstacle that requires a special gadget obviously has to be created after said gadget).
Games have differing structures and their relationship with content varies wildly, therefore every game should be approached in a fitting way.
In Transformers: Earth Wars, we already had an art production spreadsheet ...
