Oh so simple, but oh so effective. Seeing your stack of enemies approach the top of the screen, only for that fabled 'top egg' to appear... The satisfaction of watching the bastards get compressed down into an egg, and inexplicably
transformed into a Yoshi (with all the horror that mental image entails)... Brilliant.

The 3DS Virtual Console version having multiplayer was a stroke of genius - battles against friends were the stuff of legend in the Sixth Form common room.