Moving to the business area of the site.

In many ways the business side is more complex than the software development side. Making a game means overcoming a bunch of technical challenges. Once those challenges are overcome you have a product.

Businesses tend to ask many hard questions before starting the game. Questions like:

* Who is the target customer?

* How many of those target customers are there?

* As part of multivariate business calculus, how many customers will likely purchase the product with various amounts of advertising?

* As part of multivariate business calculus, how many customers will likely purchase the product at various prices?

* As part of multivariate business calculus, how many customers will likely purchase the product with various feature sets?

You're saying you are choosing to create the product regardless of the market for the product. Business-wise that is a poor decision. If you are building it for your own educational purposes then that's fine.

Should I do an alpha release? Should I start a business? Greenlight it on steam? Advertise?

Those are business decisions you need to decide for yourself. I recommend you don't invest more than you are likely to recover.

How about releasing it in a way that costs you the least amount of money and time, and trying to get feedback on the game before making the hard business decisions?

As far as I read it, this game is as of yet untested in the market. Instead of trying to come up with a 5 year plan of what you would like to do once the game is finished, finish it, and put it in front of players. Let them play it, and try to get as much feedback from them as you can.

Your game might not be fun at all. The sooner you find out, the sooner you can steer in a different direction with it. And no, your and your families opinion sadly does not count. You need strangers playing it to get a thrustworthy opinion on it.