Gameplay is like a set of questions. What obstacles are in your way?(enemies, tasks, quests) how do you overcome those obstacles? (kill, complete, unlock) why do you need to overcome those obsticles?(the goal) Where is the goal?

I think Gameplay is the way those questions are answered. But answering them in a way that is interesting and possibly unexpected. driving a car around a circular circuit is not very fun as far as games go so why not add some obstacles? other drivers, debris, weapons, turns, chicanes even a loop and you have a the starting point of a game (sounds like mario Kart) Gameplay is making the journey from the start of the story to the end of the story as interesting and original as possible so that just as you get comfortable, you find out you need to unlock a door or kill a boss and it is important because it is what stops people from putting down the controller and keeps them going to the game shop for more.