Proto:Sonic the Hedgehog 2 (Genesis)/Beta 6

Cheat codes

 * Level Select code: Up, Down, Down, Down, Down, Up, highlight 1 player, then press A + Start. Level select is still similar to that of Sonic 1 in this build.
 * Debug code: C, C, Up, Down, Down, Down, Down, Up, highlight 1 player, then press A + Start.

General Differences

 * Appears to be the first prototype with the options selection.
 * "Sonic and "Tails" in" (or "Sonic and Miles," depending on region)
 * The special stages remain the same, except with a palette change.
 * As in Beta 4 and Beta 5, the player can run right past Robotnik in Death Egg.
 * The final boss only takes one hit, most likely to facilitate testing of the newly-programmed full ending. In previous builds, Sonic and Tails just fly off to the right.
 * Super Sonic's ending is not implemented, Sonic's regular ending is used instead.
 * Tails' ending is not implemented; he uses Sonic's.
 * The Spike bug from Sonic 1 has been fixed.

Bugs

 * The "You got a Chaos Emerald!" screen is glitchy.
 * The collision detection in Emerald Hill Zone is a bit wonky in some places.
 * If you complete Wing Fortress Zone as Super Sonic, you'll end up jumping over Tails' plane, and fall to your death.
 * When Super Sonic clears a level, he will not go back to normal Sonic and the ring counter will still continue to drain until it hits zero.
 * If Sonic breaks an invincibility monitor and goes Super, he will have the invincibility stars. This bug is also in the final.