In the past when i've heard the term gameplay, i've always considered this meaning as how the game is actually played, which seems like a simple defintion to me. This would include things like game mechanics and how you would process an action.
Therefore I am reassured that my own personal view is closely similar to the definition given on the wikipedia website. However i do think it is strange that the term is meaningless, i perhaps think that the reason behind this is that games are more interactive then other activites. As even an action command processed through the game world effects AI or the surrounding environment.
I believe that gameplay is an important part of game design, that even narrows down just to simple factors like the game interface. Like for instance when thinking about game controllers and the buttons you press just to process an action, when you create the desired action you don't want to constantly press multiple different buttons just to process that single action. I think that simple factors like this are important in helping you decide on whether you actually like the game.
I reckon that there is mostly likely a basic guideline for gameplay, like i mentioned before about not making the mechanics of a game too complex so that interest is lost (at least for entertainment purposes). However i don't think that there is specific rules that must be followed, as gameplay varys depending on the game genre, though i must admit that gameplay over a certain genre type is very similar. Even though there are games with experimental gameplay this doesn't mean that they are necessarily successful. however i have found that slight changes in gameplay have been used to gain the edge over the competition. An example of this is in RTS game Battle for middle Earth, as at the time they had created a new interface of processing actions, which resulted in quicker gameplay. This new interface now happens to be current in all RTS i've seen recently.
