Without identifying era or system, how about any game you play and just know what to do without needing to look at the rules card? And not even counting the rules cards that need to have so much written on them that you can't see the font, lol. Simple is better in my opinion, like Pirates already mentioned. Not necessary a simple and shallow rule set. Just one that doesn't need a long winded explanation on what to do.
Space Station comes to mind for this as does White Water. Maybe this is a combination of the lights telling you what to shoot for as well as the sounds or voices? And shots that aren't impossible to hit. Always a good learning feedback when you need to do something, can actually do it, see the reward/result and then keep progressing like that.
I'd also vote for games that clearly show you your progress right on the playfield in front of the flippers. Lethal Weapon 3 comes to mind for this. The main modes you are trying to advance through are right there, getting lit as you do them. And doing them is pretty straightforward from hitting ramps or orbits or saucers. Similarly with World Poker Tour. All the main modes (which there are three significant ones in the game) are right in front of you. Now, advancing through them in what is a crazy long and deep rule set to get to all the different multiball modes and jackpots is another matter.
I can think of more than a couple games that I have played and still don't know what the heck I'm supposed to be doing (Monopoly and Wheel of Fortune, for example). Might be the environment or maybe condition too as having a weak upper flipper ruins any chance of liking a game (Simpson's Pinball Party was like this for me in the one I found to play not long ago. So too with a Baywatch). So condition is a factor as well.