Sonikku Team has posted a Metal Sonic Quest 2 demo up for download in their SAGE booth. Included in the demo is a MSQ3 preview, but only a password embedded in the booth will open it. Also, in the words of Sonikku Team VP CyberKnux:
And finally, another version of Metal Sonic Quest is planned! As you all know, the graphics in Metal Sonic Quest: Special Edition aren’t the best in the world (although, the graphics do work pretty well for the game). We are planning to make a graphically enriched version of Metal Sonic Quest: Special Edition! We are also planning on making some of the levels in the game longer, since a few of the levels did seem kind of short.