This game is free through the developer's own webpage. Currently is US$2.99 in the Steam store.
Review are mostly positive in Steam.
Bonbon is a short, first-person domestic horror narrative in which you navigate childhood events beyond your capacity to understand.
Bonbon is about experiencing the objects and events around you. As your parents increasingly demonstrate their absence, you spend time with Bonbon, a large, overbearing and ambiguous visitor…
You can play with mouse and keyboard, or a 360-style gamepad.
The game takes between 20 to 40 minutes to complete, depending on how you play.
I am sceptical of 'free stuff'. From my experience there is no such thing.
The price may be personal information (if any) that may be required for registration, or collected by this program (which you must agree to in T&Cs).
Some rogue 'free programs' may use your CPU/GPU to mine cryptocurrencies (slowing down your device).
It would be interesting to compare the Steam file hash with the one on the developer's website to see if they're the same.
Then again it may be completely innocent, they may just be working on a new title and want to promote it by increasing their website traffic (or increase revenue by serving ads on their site).
Funny thing is, if I had to pay two or three bucks for it (or whatever the usual price is) I wouldn't have these doubts as I do with free stuff, even though there is nothing stopping any developer from doing that with the free or paid version anyway (so it may be just me being overly paranoid).
Ps: I have not read or heard anything to suggest that there is anything wrong with the game.