Gameplay is the fundamental part of a computer game. Without gameplay a "game" wouldn't have a defining nature. Gameplay is usually the mechanics which allow the player to feel in control and drive the game forward. However, gameplay can either be enjoyable or poor, and this is usually determined by the developer’s skill in structuring the gameplay.
Gameplay is usually found to be more fun and fruitful throughout many higher budget AAA games, coming from developers like Ubisoft, EA, Crytek, 2K and many others. But these are usually based on structured gameplay used in many games of their selected genres. However, more often in recent years, smaller, independent game developers have started to think of new original and unique ideas which bring a greater depth of creativity to the way these games are played.
Game play is one of the biggest design features of any game. The game mechanics are built up of elements of story, combat systems, art style and many other things. But game design is usually in almost every aspect of the creation process. You will have story which gives the genre, scope and generally the style of the game. Based on this, artists in many departments can begin to design combat, characters, visual style, etc.
However, this is not a single person’s job. There are many dedicated teams, including; level editors, designers, technical artists, modellers, lead designer/design manager and many others. These all have a job of their own and all add their own little unique elements. When they come together, the game builds up so that the game can immerse a player and make them feel like they are actually in the game. With this idea, gameplay is not just the players interaction with the input of controls in a game, but the emersion and feeling of being somewhere else, that they are changing and moving the game alone and effecting the world as they play.
Not all games will have dedicated or segregated teams however; some smaller independent studios will more likely have less staff, and possibly some employees doing more than one job! This means that development time is longer and less games can be made in that space of time, however they get past this weakness by, in my opinion paying more attention to detail and making the gameplay elements present themselves more and to a much higher quality.
However, gameplay can depend on the genre of the game entirely. A horror game cannot allow the player to ride on unicorns as that takes the whole atmosphere and makes it unbelievable. Just as a Hello Kitty game can’t include levels where zombies jump out of dark rooms and expect players (a target audience of young children) to proceed in blowing their heads off with a shotgun. The designers have to understand the mood, style, and colour palette of the game in order to make it appealing to its target audience or fans.
I think the most important thing for a game developer to understand, is that players buy games because of the genre or style. It usually depends on age, with teenage boys liking FPS titles such as Call of Duty and racing simulations such as Need for Speed. I think the most important thing for gameplay is to get the game you have bought! It’s the best feeling as a player, when driving a car in a game moves like the real thing, or shooting a gun gives realistic recoil. I believe that a game developer should make sure the gameplay is as good as it can be before improving graphics. But it is still very important to have decent sound and graphics as it really adds to the immersion of games.