Great demo, I'm running it with Proton GE on Arch Linux and the game runs quite well at around 120 FPS. In the last level it runs at around 80 FPS, and I actually have fairly modest hardware, an RX 6600M + Ryzen 5500. This is with 100% render scale at 1080p and TSR enabled. Personally, I think the optimization is quite good. However, I've seen other users reporting crashes or poor performance.
As for the gameplay, it's fun and the art is nice. However, I think the protagonist and the gameplay are missing some "weight". You can run around without consequences and I don't feel that stamina has a real impact on the gameplay. Likewise, the weapon attachments don't seem to have any impact at all.
There is a lot of loot all over the map, which takes away from the purpose of the bullet and magazine management mechanics. On this point, I like another indie game Beyond Citadel, which has similar reload mechanics, and where you have to be careful with your available magazines.
I like it when the weapon jams and you have to fix it manually or switch to another weapon. That small moment of tension adds flavor to the gameplay
I like what you have in your hands and I will follow the project closely