Needs to be fun above all else. Interesting or unique game mechanics are nice too. A huge and largely explicit story isn't always necessary, but if there is a heavy narrative it ought to be at least decent. Graphics are nice, but it's the art style and world design that take the visuals of a game and make it engrossing and captivating. I prefer a good looking game to an ugly one with high resolution and super detailed textures. A stable framerate is pretty important, but idc whether it's 60 or 30 fps personally.