Woo :D Well, thanks so much for taking the time to leave a comment + for your support :3 It's very much appreciated!
The main inspiration for the game as a whole came from a mixture of my love for yandere characters in general + some Japanese drama CDs that I've listened to in the past where they have a white side and a black side to the CD. The white side contains the character speaking to you in sweet scenarios and is full of fluff, whereas the black side is where things tend to get a little bit psycho x3 I really wanted to try my hand at making my own series of characters who each have a white side and a black side, haha. Which is where the sweet & sinister bit comes from.
As for Castor & Castoria specifically, the biggest inspiration between them was the track that I use in Winter Wish when creepy shenanigans are about to happen, haha. I bought a music pack to use in my projects in general, and the moment I heard that track, it just sparked a character and story in my head. I decided to call the track “Glitch in the System” for the purpose of the game, but I'm not sure what the original Japanese name of the track translates to because the Japanese language pack on my PC broke at the time and just displayed nonsense characters >.< I'll have to go look at some point though!
However, I do love both Period Cube + Dot Kareshi! Heck, I'd go as far as to say that the Dot Kareshi series might be one of my favourite otome games of all time even though it's pretty casual in terms of story :D So, it's entirely possible that either or both of those games influenced me subconsciously, haha. I also did a 'gamer' route in my first game (Solipsism Reigns) and that route was inspired by stuff like .hack and SAO, so I wanted to expand on that a little, but instead of making it about an MMO to have it be about a visual novel :3
Thank you again for the support :3 I'm very excited to bring more of Castor & Castoria's story to life as well as introduce some of the other characters that I have planned for the future of DD ^-^
PS. I love your username :D