More information
here, on BioShock Wikia's page outlining it.
I believe to have the maps listed:
- Fontaine Fisheries (DE_Freezers) - Likely the arena-type area you fight Peach Wilkins
- Pauper's Drop (DE_Ghetto) - Unknown
- Smuggler's Hideout (DE_Subbay) - Likely reworked caverns of the hideout.
- Fighting McDonagh's (DE_Tavern) - Unknown.
- Dionysus Park (DE_Gallery) - Likely a reworking of the undamaged version also seen rendered in Deco Devolution artbook.
- Siren Alley (DE_RedLightAlley) - Unknown
I believe the masks are already in the game, as others and I have found "Rebirth" masks in the game files. They're golden versions of the Bunny and Bucket masks. We assume Rebirth is a Call of Duty rip where you restart from Rank 50 back to Rank 1 just for these masks.
The three new achievements are likely the ones discovered by the user Relight. These are:
- Rank 50
- Adam Addict
- Killing Time