One of my favorite unique features is the backglass bagatelle in the 1952 Genco Springtime. Flippers keep the playfield pinball in play while you hit various bumpers to advance glass marbles onto an elevator where they are subsequently collected on a trough in the backglass. The marbles on the trough are released when you lose the playfield ball through the rollover between the flippers. At this time, the collected marbles fall through a bagatelle (similar to Genco's 400 or Silver Chest) and land in various lanes.
You will replays (payout) depending upon the number of lanes that get lit. Should you get 1-12 lit, you'll get 20 replays...a feat that I've seen once in all the years that I have owned this game, but winning a few replays occasionally does happen.

I made a video from a few years ago that sort of shows the unique game play:

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