Sonic X-treme enemies
From Sonic Retro
Through the course of development of Sonic X-treme, quite a few enemy concepts were created by the team to be implemented into the game. Though many were sketched out, only a select few were then turned into sprited enemies to be used as obstacles against Sonic the Hedgehog as he ventured through what was meant to be his first three-dimensional game.
Various early concept art by Chris Senn.
Early enemy design meant for Tiara Boobowski when she was considered as a playable character.
Though nearly all the sprites below are colored red, the enemies in the game were designed to have two forms, determined by color. For example, if an enemy was colored blue, it would represent an easy enemy, while if it was colored red, it would be a harder encounter. Each zone was to have its own set of easy/hard color combinations, making each encounter a memorable and unpredictable one.