Sonic Mania, the 2D retro Sonic game out earlier this year, may be getting DLC. A mysterious SteamDB entry for an expansion to the game called 'Project Plus' has appeared on the game's page, indicating that more Sonic Mania content may be on the way.
The SteamDB entry for Sonic Mania can be found here, and the Project Plus entry was first noticed on Twitter by Sonic modder and podcaster PTKickass.
The SteamDB entry for more recent 3D Sonic game Sonic Forces revealed multiple DLC entries for the game were coming, one of which was revealed to be merely a "Sanic" Meme T-Shirt for the Avatar character. Those DLC items were merely marked as "unknown apps" whereas the Sonic Mania expansion has a name - 'Project Plus'. Since there is no avatar function for the game, it surely must either be new levels or a new mode.
Given that Sonic Mania performed amazingly well critically and commercially it's surprising that no DLC for the game has been announced so far. Sonic Forces on the other hand seemed to flop really hard, so we can't imagine SEGA are eager to pump more money into that game even if we are expecting a Super Sonic "real" ending to show up soon.