You can read the preview in the link below, but be warned that the spoilers indside the issue pretty much give away the end results of the current arc:
http://www.freecomicbookday.com/comic_sonic.asp
SONIC THE HEDGEHOG FCBD 2010 EDITION
Creative Team: (W) Ian Flynn (A) James Fry, Jim Amash
Publisher: ARCHIE COMICS
"Hide & Seek & DESTROY!": Dr. Eggman has vanished - or
has he? As Sonic searches for clues, he stumbles across an old weapon
from the bygone days of his childhood. Will Dr. Eggman allow Sonic to
be destroyed by this threat from yesteryear? Will Sonic discover the
truth behind his old rival's disappearance? All the answers lie in this
free issue!
32pgs, FC
FREE!
So since this topic is here...I guess I can kinda revive it.
The story was kinda interesting.
Sonic plows through the area where he last busted in with the Freedom Fighters to take down Eggman in 200, and he's running down the halls. Suddenly he's attacked by this...thing. Its a vine monster that acts like a JunkBot, it grabs scraps of older badniks (Catekiller and the like) and rebuilds itself as well as grows since its a plant base. You find out it survived the nuke because its a root and the rtoiot survived so it took time to regrow and now it will takes its' revenge on Sonic.
Sonic is happy to oblige a battle and reminisces with it, commenting on all the old badnik parts it has (Swatbot lazer and Brrowbot drill come to mind..). The good doc and Snively watch and Eggman gets well, jealous and angry that his former form made this monstrosity, scrapped it, and now it survives and is well-kinda whooping Sonic up a bit. Snively loses it, wondering why he just doesn't let this plant take Sonic out, and Eggman explains that Sonic is his and his alone, that he will be the force that removes Sonic from this world.
So Sonic gets trumped and the plant looks victorious, and Eggman builds a hummingbirdbomb that flies down at the last second and pecks the plant and Zapboomdeath panel. Sonic escapes, and knows the good doctor is watching. But he leaves, to fight another day. Not bad for a free comic 
Vine Monster? Is it the Kudzu plant from the pre-30th issues or something new? Also, convenient name for a trope considering this very comic gets referenced in the appropriate section.
Uhh ::Looks up real fast::
Yes. Krudzu Hybrid Hydra.
