A computer or video game's gameplay
is the experience imparted to a player when playing the game. It is sometimes referred to as playability
, instead of the more fitting qualitative
measure, but that's just arguing semantics
). The quality
of the gameplay is the only important measure of a game's success
Gameplay depends largely on the design of the game - the structure of the environment, the controls, the difficulty, the balance of rewards and challenges. It's two-way communication. All of these factors will only be addressed well if the creators thoroughly play existing games and continually test and tweak their game during development.
Gameplay is affected to a much smaller extent by the graphical and sonic components of the game - back in the old days, these elements could be discarded out of hand, but with modern games, the "feel" of the game and how it responds to the player (e.g. with convincing physics, fear- or excitement-envoking music, graceful and synchronous animation) can contribute to the rewards and punishments dished out, as well as making the mechanics of interaction more enjoyable* (e.g. driving in Interstate '76 is relaxing and engrossing, while Dogtanianing hapless trolls in Severance is tense and cathartic). Yet still a game can get all the aesthetic elements right and still fail to have good gameplay.
Gameplay cannot be accurately gauged from a short period of exposure to a game - something that has occasionally led to magazines overlooking a slow-burning classic. Good gameplay is often addictive.
It always requires a significant expenditure of effort on the player's part, which is probably the core reason why gamers are wary of the encroachment of the general public (casual gamers) on their hobby.
If developers cater for these new players by making games easier, they run a risk of damaging the gameplay. This is not always the case however, as replayability (see almost every coin-op) and hidden depth (secrets, moves, subquests...) are areas that can be concentrated on to bolster a game.
Then we have multiplayer gameplay, which extends the experience in all kinds of interesting ways.
Now go and play a game and think about why you like it (or why you don't). Gameplay is ongoing research.
*or the best example of this ever, ever : attacking people with the Hydras in Heroes of Might & Magic II.