Blaster Master (1988) has one of the great absurd setups: your pet frog hops into a radioactive box, mutates, and dives into a hole, so you give chase in a powerful tank named SOPHIA.

The genius is the structure — you drive the tank through interconnected side-scrolling caverns (gaining upgrades that open new paths, Metroid-style), then hop out on foot into top-down dungeons to fight bosses. Two games in one.

It was also punishing: the original had no password or continue system, so a death deep in meant starting over. Brutal, atmospheric, and unforgettable. That tank is an icon.