"Attack on the Death Egg" in Sonic the Comic #6 is one of the more memorable stories from the early days of STC, not least of which because of Ferran Rodriguez's art. The backgrounds are sparse and the layouts frequently lead the eye in the wrong direction, but Sonic and Tails themselves look pretty good, more on model with the the Sega of Japan versions than anything before or after. And with good reason too, since Rodriguez clearly had Japanese "Sonic the Hedgehog 2" stock art in his reference material. In later issues Rodriguez found his own take on Sonic and began drawing Tails on-model with the American depiction. But his Japanese Sonic 2 reference material didn't stop at Sonic and Tails. In STC 29, Sonic saves a Becky, with little design details that aren't visible in the in-game sprite. As far as I'm aware, the only place we've seen Becky's illustration is the Sega TV Game Genga Gallery art book, which showcased 8 of Sonic 2's 12 animals, and was released over a month after this issue of STC. Rodriguez also drew the "Doctor Sun" story in Sonic the Summer Special. The story begins with a badger named Mr. Stripes asking Sonic to investigate a cult his son has joined. Aside from the young badger, the cult members are all animals from Sonic 1 and 2. Here's a Lucky/Locky in the background. The indentation in the head is another of those little details that isn't seen in the sprite. With all of this in mind, there's one thing of particular interest. There's a mouse featured quite prominently. Given the context, I don't think it's just a throwaway background character design, it's very likely the mouse from Sonic 2's Mystic Cave Zone. As I said earlier, Sonic 2 had 12 types of animals, Sega TV Game Genga Gallery had illustrations for 8 of them and Sonic Jam had illustrations for 7 of them (the seven from Sonic 1, but it's Sonic 2 era stock art). Between these two sources, the mouse is the only one whose illustration hasn't been found. But it seems that for a while, it was available to Sonic licensees as reference material. (Or maybe Ferran just found it in a Spanish video game magazine - who knows!) Until that missing illustration turns up (if ever), this is probably the closest thing we have to an "official" design for the character.
Ferran is quite active online these days, one could ask him if he remembers anything about this back then. That said, that Badger there is not from anything games-wise so I wouldn't take it for such certainty that that mouse is meant to be the Micky from Sonic 2.
Was the name ever discovered for that rat/mouse? I believe it had a name in the Mania data files, but no-one could really confirm if that was the real name or not. Either way, quite an elusive creature!
Yeah, in Mania's code it was "Micky", but I don't think there's been any confirmation whether that was the official name from 1992, or just one of the devs having a bit of fun. On a related note, Tocky, Locky, Becky and Wocky aren't official romanisations for the other four. The 1994 art book (which is JP/EN bilingual, but only released in Japan) went with Tookie, Lookie, Beckie and Wookie. These aren't the spellings Sega/Sonic Team would use today of course, since Sonic the Hedgehog's GameWorld and Sonic Jam established that the Sonic 1 animals' English names all end in "cky". Becky and Tocky are fine, but for the bald eagle and monkey, Lucky and Ucky might be a bit more accurate. (???? is Japanese onomatopoeia for the noise monkeys make, that just so happened to fit the naming convention of the Sonic animals.) Spoiler Sonic Team probably still has this artwork filed away somewhere, since the monkey made a surprise appearance in Sonic Rush's ending. (It also appeared as an icon on Sonic Team's website in 1996, so it's especially odd that they didn't include it in Sonic Jam.)
