Sonic the Hedgehog 3

Sonic the Hedgehog 3 is a video game published by Sega. The third main game in the Sonic the Hedgehog series, it was released for the Sega Genesis in 1994. Development of Sonic 3 began shortly after the release of Sonic 2 in November 1992. It was developed simultaneously with Sonic & Knuckles, as the games were originally developed as a single title until time constraints and cartridge costs later forced the team to split them in two projects.

Original description:

New attitude! New enemies!
Swing from vines, launch new attacks, survive deadly traps and summon Tails to airlift Sonic out of danger. Discover hidden rooms and passageways in the mega-sized Zones. Transform into Super Sonic and experience the ultimate in speed and ultra-sonic power. Save your progress using the new Game Save Feature.

Warp into the new Special Stage and dodge the 3-D Energy Spheres to collect the hidden Chaos Emeralds.
Outsmart Dr. Robotnik, who's back with all new inventions.
Meet Dr. Robotnik's newest recruit, Knuckles. He's a native of the Floating Island, where this spin-dashing escapade unfolds.
Play as Sonic, Tails or Knuckles in the all-new, 2-Player, Split- Screen, Simultaneous Action Mode featuring totally unique Zones.

Instructions

Enter - start;    Arrows - move;    Z X C - jump;    Esc = exit fullscreen;

You can change keyboard settings, save (F5) and load (F8) the game.
Put your mouse over the game and choose your settings, you can also play the game in fullscreen.