Maybe I'm just not getting it, but I was so lost in this playing this. I just couldn't figure out if there was some sort of strategy to this, of being able to tell how close you are to tripping the alarm, or if it was all up to just dumb luck on whether you get caught or not. I expected there to be some sort of tell or levels to the guard's reaction for how suspicious they are getting, or for there to be some sort of mini-game you play when snatching loot to reduce noise, like a timed button press you'd see in Dead by Daylight or something, but there wasn't any I could tell. Even with boot upgrades, it seemed like once I tripped the alarm it didn't matter how fast I returned, I was doomed, and with no banana peels or marbles or anything to ward the guard off. I understand you might not want to make it overly obvious how much guards get suspicious to keep it mysterious, and to make you experiment, but for me, it might've been too mysterious and led to frustration and a feeling of lack of control.
In the end, because of the confusion, I opted for a very boring playstyle of just looting a few obviously easy pieces and returning, over and over, focusing on upgrading my stats bit-by-bit. And technically, I could just keep doing that, ruining the game of any fun from the risk I think it should push you to partaking in. I think the game does try to avoid that boring scenario by giving you timed contracts and upping the guard security level (which I'm not sure whether affects detection speed or running speed or whatever) but still, technically it doesn't make a difference as I could continue to lame it out by playing it overly safe for a long long time.
Again, perhaps I missed a big obvious clue for the system mechanics, and maybe I'm being unfair wanting the game to be more player skill-based when it's a more stat-based casual-based game, but I just wanted to let you know my experience. I think it's a really good concept, and I love the art, lively UI, and goofy touches like the guard shaking his fists at you if you escape (and the tutorial grandpa guard, haha), but at the moment, it just felt so underwhelming and oddly designed, leading to my confusion and, in lieu of any readable strategy, optimizing the fun out of the game.
EDIT: Ok, went back, tried to face the game on its own terms, and won in 60 days. I suppose maybe I was just being impatient and such. I'm leaving the initial confusion and such up above because I still think it's something to think about (or laugh at, haha), but once I got used to how the game works and accepted the vague rules and stat-based grind, I had a good time in the end. It's definitely quite impressive how you made a game good despite such limited controls, and I think it's up to the charming presentation of the game that hooked me back to try again, so well done on that.