Absolutely incredible gameplay. Love the style, the mysteriousness, physics...i could go on. One suggestion (which i assume you're already planning to implement), customized controls. Other than that, this is extremely promising and i'll be back for more!
P.S. didn't die a single time on my first playthrough but it is punishing...and i like it. The tacticality? mixed with Quake and a hint of thriller/horror was well executed.