Things like Zombies, Witches, Vampires, Succubi/Grim Reaper, Demons, Devils. That took me like 5 minutes, if someone really takes his time one should get some pretty good ideas.
Not really sure what you mean with making sense. A Greek citizen cosplay to Halloween dosent really make sense imo.
I dont understand the specials as a whole tbh. It would be more reasonable to try to finish the game + freeroam, instead of prolonging the development by adding stuff like Christmas and Halloween specials.
They will transform into the costumes they're wearing and have their personalities influenced by that. Starke said they didn't want to make zombie girl because they will make a game dedicated to that so it would be a wasted slot. There will be a witch which is Luna who I think is the MC of the third game? Vampire girl is actually not a bad idea! Demons/devils/succubi kinda fit all in the same plane and as you might know, Fujiko will be a Succubus.
So that leaves Grim Reaper which would kind of be OP if one of the girls was the embodiment of death. Plus it would probably not look very sexy.
There will be monsters having sex with the girls. So far I heard goblins, orcs, tentacles, slimes and werewolf. They asked us on Discord what we would like to see and those were mentioned by multiple patrons.
The reason for the seasonal stuff being made instead of progressing the game. There was a voting on Patreon and seasonal patches won by a vast majority so that's why these are being done.
It might not make sense but there's a reason behind all of it. Just takes some research. I wasn't a huge fan of the Greek Goddess or Greek Warrior Ayame but I'll wait for the transformation version and the actual game before I pronounce myself about it. I've jumped the gun too early in many occasions in the past and they always delivered and proved me wrong. They have earned in my eyes to at least see what's going to happen before I make any judgements.
imho it's more of a masked party with the transformation and spooky monsters at midnight.
