Thank you! Terraria was definitely one of my biggest inspirations, along with Starbound and Risk of Rain 1 (and Deltarune for the difficulty). In fact, my development of the enemy and bullet behaviors heavily draws on my past experience as a Terraria and Starbound modder. So, I'm really happy that you're the second person who recognized the Terraria influence.
I'm also glad that you like the characters! They are the same characters from my past two games, although I think of each game as being its own timeline. (Although, DERELICT and Temple of Endymion could possibly be part of the same timeline.)
I used a palette called Retrotonic DX by Doph for the colors, I would definitely agree that it pretty much carries the visual side of the game as I'm not that good of an artist myself!