First of all the music slaps, and a very unique take on the theme. The game feels pretty good to play and it was a fun little stealth mission. If you figure out about the double destruction it becomes pretty easy, I did like discovering that glitch though it made me feel like a speedrunner lol.
Given the time restrictions it's solid, but to give some ideas for extra difficulty maybe you could make guards always detect you, just with a larger range when you're hammering. Then to compensate, add some hiding nooks and more maze-like levels.