A great concept for a game. The fact that enemies take a while to spot you is a good design choice---too many other stealth games are unforgiving in this regard. There are some things that need improving:
-The UI is a bit overwhelming at first. Two different contracts to choose from felt like too much to track.
-Some tasks on the contracts felt bizarre. I understand the guild wants me to steal things, but why do they want an enemy to steal a spell from me? Why do they want me to drink an antidote?
-The button in the lower right corner of the game that takes the player to your other games needs to be removed. It's placed in the worst spot (right over the fullscreen button? really?) and it kept activating whenever I pressed space bar, so I couldn't pass the turn hiding at all. In addition, I don't think anyone would be interested in viewing your games DURING a playthrough. Maybe you should put it on the game over screen only?
I scoured the whole map and couldn't find bones. I think I needed to kill a skeleton, but I didn't know how to do that. Right when I found what looked like bones, I died.
I'd say this is an idea worth exploring further. Improve the conveyance and onboarding to new players, and maybe clean up the UI.