Don’t patronize me, game!

@Background Pony #1E0C  
Granted, M2 only remade Sonic 1 & 2 for the 3DS Eshop, but didn’t do any Sonic games afterwords, so they didn’t really skip StH3. They just didn’t make anymore. (Probably ‘cause Sonic isn’t very popular in Japan.) They also only remade the first two Streets of Rage games.
 
On that note, I actually have an officially-licenced “Sega Genesis Ultimate Game Player” portable game by AtGames, it has every Sonic Genesis game, BUT Sonic 3 oddly. (Which is odd, ‘cause the RPG games included have their save file features in tact, so the save feature isn’t an issue.)

@Beau Skunky
 
On the 3DS it’s also skipped (the first two titles are available as 3D Classics). Xbox Live Arcade has it (and you can play Sonic 3 by itself). The titles are also backwards compatible with the Xbox One.
 
Other then that, Sonic 3 has been in some collections over the year. Sonic Mega Collection, Sonic’s Ultimate Genesis Collection, and Sonic Classics Collection (for the DS) come to mind.

@Background Pony #1E0C  
I heard Whitehead wants to remake it, (and S&K too) but Sega won’t let him yet for some reason. (Maybe ‘cause it’s more complicated, due to connectivity with S&K.) Maybe after “Mania” sells well enough they’ll finally do it.  
Either that, or Sega will just lazily release a direct port on Sega Forever.
 
A legal official download version of Sonic the Hedgehog 3 does exist on the Wii Shop Channel, (with connectivity features in tact) but said Channel is going to end soon. (In favor of Nintendo’s Eshop service.) There’s an official version on Steam too, but apparently it’s “Sonic 3 & Knuckles” combined, so I dunno if it has options to play the 2 games separately.

@Beau Skunky
 
I wish they would release Sonic 3, I don’t get why they don’t do so. They did the same thing with the PlayStation Network versions, randomly skipping Sonic 3.

@Vinyl Fluff  
No clue, but apparently it’s still on the iTunes store.
 
They might be planning to rerelease it under their “Sega Forever” line, like they did the Sonic 1 & 2 Mobile remakes.

@Beau Skunky  

 
They removed it? Any particular reason why?
 
I’ve got the full .APK file, from when Sega did a Humble Mobile Bundle, and they distributed the games straight-up, rather than making you go through Google Play.

@madwing  
Well, they should fix it soon.
 
Meanwhile, I’m still waiting for Sega to put “Sonic CD” (the great official Christian Whitehead remake) back on the Google Play store…

@Beau Skunky  
I hated this new update Gameloft fucked up everybody

(Anyone who sees this screen when starting up the game.) FUUUUUUUUUUUUUUUU-!!!!!!
 
The Animal Crossing game is better.