Sonic the Hedgehog

Sega was looking for a character who could hold attention on the shop shelf next to Nintendo, and got a hero whose main trait is speed. The levels are built like tracks with slopes, loops and ramps: the engine constantly recalculates the angle of the surface under the character's feet, so a descent speeds you up and a climb slows you down. The controls come down to running and jumping; all the difficulty is moved into reading the terrain. The space is also divided into tiers: the upper path goes to those who keep up the pace, the lower one is taken more carefully and takes longer.

Rings work in place of a health bar. As long as the hedgehog has at least one ring, a hit only scatters what has been collected across the screen, and there is a second to pick some of it back up. That decision removes the fear of speed: mistakes are paid for in rings. Sega started bundling the console with this cartridge, and it gained a face recognizable without explanation.