For many people, game design begins and ends with a concept. "Hey, I have a great idea for a game," it usually begins; what follows is a concept.
The concept on its own offers very little real insight into how or why the game will be fun. Often, the person pitching the concept is imagining a few other games with similar concepts and assuming all of the ancillary details of the gameplay are implied.
If you're a designer, you know this is not the case, but that's not to say a designer should be dismissive of concepts. After all, the concept is the highest level of the game design; a game won't sell without a concept that tells a compelling story all by itself.
Some of the greatest games ever designed were commercial failures because the concept didn't resonate with the consumer. Sequels and movie-licenses are successful largely because the concept is already defined in the consumer's consciousness.
In a mobile game, there is no box art or demo video: the concept has to come across in the game's name. When I was working on a game using the 24 TV show license, the greatest obstacle the team faced was naming the game.
We were already on the sequel and we knew the first game had underperformed, probably because of the name, so "24 Part 2" just wasn't going to work. Something like "24: Jack Bauer's Back" was contractually not an option. Ultimately, the game was named 24: Agent Down and very likely suffered because of it.
In our case, the concept was already set; anyone who had seen the show knew 24 was about espionage and intrigue, hacking computers and after-hours shootouts, but communicating it to the consumer in one short line of characters was almost impossible, making the concept as good as lost.
A game that worked was ER Rush. ER Rush was an original IP, hospital-themed "plate-spinning" game, similar to the successful Diner Dash. We diverged with many of the mechanics, but the basic concept was the same. The users got what they expected (a game where you rush around servicing patients in a hospital environment) and the game sold well.
The best thing to do with a new concept is to encourage it; pick out the aspects that seem most compelling and expand on them. Tell a story. Let others tell a story. This won't necessarily describe the final game, but it helps define the next step: paradigm.
Paradigm is perhaps the most difficult to name of the four basic layers of a game design and the most easy to overlook. It sounds pretentious and abstract, but the meaning is actually very specific and necessary; the paradigm is the perspective with which the user interacts with the game.
Every user that picks up your game will be approaching it with a certain set of preconceptions; assumptions that are inherent to the user himself, his society and humanity in general. Games are reflections of human life so it is only natural that most games tend to fall into the same range of popular experiences such as, hunting, hiding, collecting, building, etc. It is these experiences that define paradigms.
A paradigm encompasses a set of expected rules. The user intuitively knows the objectives and hazards inherent to a paradigm, such as managing resources, without needing to be told. If a game incorporates many different experiences, each with its own micro-goals, then it can be said to incorporate many different paradigms.
Paradigm is similar to genre, but where genre relies on past games to build archetypes, paradigm refers directly to the fundamental building blocks of human experience.
An example genre; first-person shooter, describes the visual perspective and objective, but fails to define the specific paradigms. A FPS might feature slow-pacing (methodical/planning ahead), heavy use of cover (hide and seek), strategic weapon-upgrading (resource management) and situational toggling of weapons (tool management).
Each of these aspects of gameplay is actually its own little paradigm (marked in parenthesis) and each carries with it a familiar experience that the user can be assumed to understand immediately. A user doesn't need to be explained the premise of hide and seek; it is inherent to the human psyche.
It can often be difficult to differentiate paradigms from concepts; many concepts will immediately suggest an obvious paradigm (for example, a deer-hunting game begs for hide-and-seek gameplay), but that doesn't mean other paradigms can't be used.
It is also easy to confuse paradigm with game mechanics. Often, the first game to succeed in a paradigm sets a precedent for mechanics that is rigidly copied by generations of successors. For example; does a trick-based boarding game have to be built around a four-button combinational input scheme? For many years, it did.