R2

Sonic CD prototype 510 level select, with level 2 missing.

R2 is a reference to a deleted level from Sonic CD. Proving its existence is possible by examining the game files on a PC. When examining the level files the levels skip from R1 (level 1) to R3 (level 3), there is no R2 to be found. It's existence is also proven by using the level select menu. When switching between levels it skips from level 1 to level 3, again leaving out level 2.

There are many speculations as to what this missing level might have been. Some say the Desert level was to have been here, when it was taken out of Sonic 2, while others think it was the ruins level seen in an uncut pencil sketch. Although many topics have been started about this, most have led to arguments and usually only end up in frustration. All that is known about R2 is that it was originally the second stage, between Palmtree Panic and Collision Chaos.