Cool concept; the graphics and SFX are really well done. It would be great to refine a couple of things:
1. If there's no stamina mechanic, the running feels a bit redundant—players just hold down Shift non-stop, and their finger gets cramped :D
2. Right now, you just left-click to apply paint; there’s no stealth element—you just run around spraying paint, so there’s no sense of tension.
Overall, excellent work! Keep it up!