This game is partially inspired by Apocalyptic Wind Tower, a forum RPG game created by Pteriforever (aka AuroraDash) who also created Solar Shadow and Solar Shadow 2. Sonia Routen, a character from that RPG will be appearing in Floor 19 as an NPC. This was later changed so that her only appearance now takes place on Floor 13.
The game has a time system, akin to Legend of Zelda: Majora's Mask. At the start, players can have free rests but at some point, resting will advance time by one day. Resting on 17/12 however causes a Bad Ending.
Floor 13 and Floor 17 are maze areas.
Floors 5, 11, 15, 16, 19, 20, 22, 24, 25, 26, and 28 considered Boss Floors.
The main protagonist's gender can be decided by the player, with each gender having 3 default names: Frio (Male), Kyaro (Female), Victori (gender neutral).
Several characters from Lunar Shadow will be returning, though it's currently unconfirmed in Serenity Horton will be the main character this time around.
Kim Tyranto may appear in the mod as it's final boss. This may change during the final release.
The mod is being developed Kim and two of her friends, with the mod itself halfway finished (19/30).
This mod will be Kim Tyranto's final Cave Story mod. It's unknown if she intends to move onto other gaming mods, create her own games or retire altogether.
A character called Kim Ethnarch will be appearing, and her allies Alyth Remiel and Kate Peregrine will also make their debuts in this game. It's unknown if she's connected to the final boss or not. Much like Aidan Flamberge, she's also rather foul mouthed.
Another boss Kresnik was confirmed. It has 4 phases, each faster than the last.
The Champion of Serenth has 8 days to stop the apocalypse of Serenth.
The areas are currently unknown, though it's confirmed that the Tower has 30 rooms.
There will be multiple Apocalypse Towers, with Serenth's being confirmed as the Moon.
Champion of Serenth
Fantome (a recurring boss)
Cycreep (Boss of Floor 15)
Kresnik (Floor 19 boss)
It's possible that Apocalyptic Shadow Tower is the canonical sequel to Lunar Shadow, with the other mods Kim planned being rendered non-canonical.
Due to life issues, the game's original Best Ending would have had the main characters die.