There will be a large number of hours spent just getting to a beta status, which should be accounted for at a reasonable rate. This amount, no matter the structure, will not likely ever be covered by revenue. Then, if they get to release status, the only reasonable way to make money these days (for new ideas) is via mobile apps and ad revenue, which takes time and multiple titles based off the same code (low cost to develop additional titles.) The chances of them being the next "DOOM" are too small to consider - if it happens, they can deal with it then.
When asked about getting into the software market, my answer remains unchanged after decades. Develop something you know, use, and can't live without yourself, share it with others, and if it is to be profitable, it will become apparant when you share with others. Then, after sharing, if it seems profitable, setup a "real" business. If developing other than by yourself, setup some sort of structure which can be enforced if the item becomes a product. Setting up a business first will only take away from development.
Just one person's opinion, who happened to get into the try before you buy software industry at the right time...
(Also applies to an old passion of mine, auto racing - and too many who tried to setup businesses for a hobby with zero chance of making a profit. One interesting item in auto racing, is when racing as a business, the often unforeseen pitfall of needing a commercial drivers license to transport the car... and all the CDL regulations involved such as hours, weight stations and inspections, etc.)