I'm only familiar with the Ross Game Dungeon video on Messiah but I definitely want to see more games like this. I think with this kind of game the level design is make or break for whether its fun or not. I really like the little sandbox and I thought the door opening with the camera was really impressive. The shooting completely broke for me and every character ended up invincible and T-posing but the guns felt nice. Platforming on the pistons kind of sucked since the player bounces constantly while it moves down, it reminded me of the teeth platforming puzzle in System Shock 2. If you can set up a few fun shootouts that'll be an improvement on Messiah.
I noticed that the game stutters when you fire any type of gun for the first time, which I'm pretty sure happens because Godot is compiling the particle effects / shaders when they are first called. You can preload and instantiate them while the game is first loading to prevent this but it does make your initial load a bit longer.