I am a programmer and have worked on games although never attempted design myself. I am now attempting to design a game myself, working with a modest team of programmers and artists.

Game designers have been telling me it is important to establish the need your game fills, in order to develop a more complete vision of the product. I think in terms of mechanics and gameplay and am having trouble finding a "hook," even in existing games.

Any advice in identifying why a mechanic is fun, and what need a game fills, to help develop my own ideas is much appreciated.