Semi-Frequent Sonic Forces Facts & Moreさんのイラストまとめ

The unlock for Sonic's shoes is an entirely different model, for some reason. Nitpicking, I know.

THEY HAVE BLOB FEET, YOU CANT DENY THE TRUTH!

Like Big exists guys

SA2's soap shoes make a reappearance for the first time since their debut as an unlock.

Likewise, as does this bodysuit. It also features the Genesis/Mega Drive 16 bit icon on the back. The text is unfortunately illegible, but I assume it's probably something SEGA used for the Mega Drive in its marketing.

These shoes sport the logo for the Sega Mega Drive.

This is probably a coincidence, but the first pair of heterochromia eyes resembles Infinite's.

The AiAi DLC hat was supposedly repurposed from the Monkey avatar concept (doubt)

One more. Unfortunate we didn't get this realized.

This is just speculation and not fact, but I think that they may have intended to overhaul a lot of the areas in the game before development kind of took a turn for the worst and they had to cut things back.

Also, here are the rest of the paintover artworks:

A lot of Sonic Forces' concept artwork are actually paintovers of certain areas at points either in development or of finalized areas. The most notable example of this is the Eggman Empire Fortress battle concept art, where you can see the final game's Imperial Tower & Warships.