- A license
This is usually a video game based on a movie or comic book. For example, the Lego series of video games or an Avengers video game.
- New IP (Intellectual Property)
In this case, I am referring to the first time this game/concept has been done. For example, TitanFall is brand new and original.
- Existing IP
This would be a concept/idea that is owned by the publisher or developer. For example this could be Sonic the Hedgehog or Call of Duty.
In the first stage, the concept paper acts both as a letter to yourself setting out your goals clearly so you won't lose sight of them - and as a sales tool for whomever takes the product to market down the road.
Sometimes, this stage involves a working mini-prototype as well, which gives you a chance to experiment and revise your ideas.
Find more questions by tags Development of games