[Literature] Fundamentals of Game Design, ch3: Game concepts

In order to answer the questions "Why would anyone want to play this game?" and "What's going to make someone buy this game instead of another?", a game concept contains to a minimum:

high-concept statement

description of the game in 2 or 3 sentences

player's role(s) in the game

describe the avatar. Think about player's actions first, not on the story. The more obvious the role, the easier players or publishers can decide if they buy it.

primary gameplay mode

with perspective, interaction model and challenges

genre

category of games characterized by a particular set of challenges regardless of game-world content. Examples are action, strategy, RPG, simulation, sport, tycoon, adventure, puzzle. Mixes are possible. If new genre, describe why.

target audience

Who am I trying to entertain?. Avoid repelling people who might be attracted by the game. Examples of player populations: male/female, children/adults, different cultures, different (dis)abilities, [hardcore/casual].
Localization not only translates but also takes into account other cultures' particularities.

hardware and system requirements

console => TV => 2-3 people around at the same time => small-scale multiplayer game. Local play is more common than networked play [is it still currently the case with systems such as XBLA?]
PC = small and personal high-res display, personal, the PC player can write thanks to the keyboard
pocket console: small cartridges => less room to store audio or video data like cinematics
mobile phones: wireless => can compete against other people
plane seats, gambling machines and arcade machines are niche devices containing games

licenses

if any

competition modes

(singe, dual, mutliplayer, coop, ...)

progress and synopsis

but not a full story

short game world description