Okay, I'm sure this will be of interest to some people: I found out the original inspiration for this type of game. It all started with a DOS game released in 1996 called Tower of the Sorcerer. But I only figured that out from finding another game in the genre that explicitly cited it as an inspiration, and it's that game I really wanna talk about.
It's called Tactical Nexus, and I decided to give it a try since the first two chapters are free to play on Steam, and... Well, my first attempt at the Tutorial Tower ended with me unable to beat the boss, after almost two hours. My second attempt, helped by the knowledge gained the first time and me taking my time to try and optimize things, just barely managed to defeat the boss after over four hours.
I know I'm not the best puzzler in the world, but that was the Tutorial Tower. This game is the real deal.