I'm not gonna take anyone's side here specifically. But I do slightly see the point of Playful's argument. I'm not gonna be an azz and say it's 'tantamount to a scam'. But I do think for a brand new demo build game. The price of 12$ is kind of wild, regardless of whether or not it's for purposefully supporting a games development.
That being said i've not the slightest clue how to even make a single line of code. Let alone program and build a game. So obviously, making a game, by your lonesome even. Can certainly be a challenge. So spending 12$ is probably cheap in some other games cases.
Long story short. I think it might be better to lower the price even by a dollar or 2. It can be a real jaw dropper to try and support someone and their already asking for over 10$.
That being said I'm spending 12$ and supporting this game. Because it looks neat and I absolutely want to support it. I hope your game gets the support it needs Yua Nizu