The Pinball Adventure, despite its confusing name, is actually more of a pinball RPG. Kind of. Each table gives you quests, like an MMO: kill 10 of this type of monster, then kill 10 of that type of monster. Complete these quests to unlock the boss monster, kill it, and then move on.
It'd be good to see the developers continue to add features, such as skills or other character upgrades, to further enhance that RPG-ness. But, somewhat spongey physics aside, this is a good start.
The Pinball Adventure [Kongregate]