Mario's Lair is far more high-tech than one would think. For a guy who began as a carpenter and ended up a plumber, there's a lot of high-tech electrical equipment going on here.

Junior must follow a linear course, avoiding cross-orbiting balls of electricity and free-traveling blue sparkles launched continuously by Mario at the top of the screen.

Junior looks worried. He should be. His path is pretty much linear: he has no options but to climb and cross, back and forth, until he's at the top—and look at the things he has to avoid.	Each section has orbiting balls of electricity, orbiting in both directions. Meanwhile, blue sparks are launched by Mario up top; these can orbit the pink sections but can also follow the blue speckled trails you see—allowing them to travel from section to section, hunting Junior down.
Junior is almost there. There are three pieces of fruit here, but it's tough to get without jumping head-first into electricity orbiting above you.	But he does it here! Leaping a baddie, Junior hits the fruit and nails him.
Relative safety. So long as his clock doesn't run out, junior can hang here to plan his route.	Another jump!
Junior achieves the pink key. But there's to be no rescue of Papa this time. As per usual, Mario will take Donkey Kong away.