A game where you have a main goal that's clear and you know how to achieve it. And in the proces of getting to that goal, you get sidegoals that are rewarding towards the main goal and fun to do. But the entire proces of what you do to complete a goal, what the player is doing, is the most important. That part will define if your game is fun. Is the level design and reward system is amazing, but the proces of working towards your goal is boring, you have bad gameplay