Hi!
Loved this thread, thanks for being inspired by my question! For Doors, Monsters and Towers we had many inspirations. I am a fan of Monster Taming games, I follow the best Monster Taming youtuber, Gym Leader Ed and was inspired by games like Monster Sanctuary and Cassette Beasts in that regards. With the other main dev qe have been playing Pal World, so that was an inspiration also.
In terms of visual design and gameplay mechanics, we looked at Foster's Home for Imaginary Friend, Pizza Tower, Hollow Knight and Wario Ware for visual style, Plants vs Zombies for the line attack sections (you are the zombies) and of course Mario Games for the 2D platforming.
I actually studied Plant vs Zombie gameplay to design further interactions for the line battles section, but we fell short on time to implement most ideas, we had a healer monster, a ranged monster and a shield monster that didn't get into the game for the Jam. We also had some ideas for platforming that are saved as "Future Work".
Would love to hear more jamers talk about their inspirations!