If you were looking to buy Sonic Forces in Electronics Botique stores in Australia, you may have seen this cardboard big sign. It's an announcement sign for the game or pre-ordering the game.
The front has the Forces gang complete with 'generic the character' & a wisp in there. The other side tells you about the game, has screen shots & explains what you get with the bonus edition. The bonus items are costumes from other franchises like NiGHTS & Jet Set Radio so you can dress up your custom character. (But then why have a Shadow costume? Why not just...put Shadow in the game?) Once store signs like this are expired (the game releases) they can sometimes be collected, as what happened here.