I was playing Congo for the first time a while ago. I managed to activate some weird timed mode, where power of the flippers was turned off, causing the ball to drain, after which I was supposed to use the plunger to hit a cycling target on the left side of the playfield. The machine kept feeding balls to the shooter lane as long as the mode lasted. So suddenly the machine turned into some sorta bagatelle. This was really cool.
After playing the Congo I started thinking what other really unique, crazy and cool modes I've encountered in pinball machines. One that came to my mind was a mode in Stern's Star Trek (Pro), where a kicker behind one of the main targets shoots the ball back to the flippers at great speed every time you manage to make the shot. Normally this occurs during one of the multiballs, but later you have only one ball during the mode. This is very cool, it really feels like "man versus machine"
All this started me wondering... What do my fellow pinsiders think are the most unique, craziest, coolest and innovative modes in pinball machines?