Must include in project
Level Design Document (see below)
Level Design Document
Audience: who is going to be using this document? Programmers, integrators, game designers, environmental artists, game/creative director, producer and of course the client.
Motivations: what does the document need to be used for? Building the level and environment, programming the level, testing the level, cost and manage the process and sell the concept.
Consider readers and writers: readers need information to do their jobs and writers need a process to do theirs (but they may also be readers).
Motivation: forces a pre-production process and separates design from making.
The Last of Us is a good example of a title page. The highlight on Ellie shows that she's a main protagonist (and also a bit of a badass). You can also see from her expression that she's been/is going through a lot. Joel on the other hand is reserved and is holding back in the dark, which reflects his personality and traumatic past. You don't have to have played the game to see this, which is what makes it a good title page/poster.
Not all of the below needs to be implemented, but sticking to this structure will aid in creating a good document
High level devices
X – hard to define unique aspect of the game
Combinations and permutations
Systems and entities