Cool concept and solid progression logic!
I missed the shield in the treasure room at first (maybe make it pop more?) but the gameplay loop is interesting.
The timer felt a bit punishing since I can't control when or how fast the intruders will appear and sometimes I felt like I was losing just because they were taking their sweet time... I think it would be cool if the intruders were the ones on a time limit instead!
Loved the +5sec mechanic for the "!", though, definitely kept me in the game.