The company type is important when you spend tax deductible expenses and when you pay taxes on business income. And when signing contracts with vendors. If you are just going to work solo, you can set up the company type when the time comes.

Legality will be an issue if you get more people working on the game with you. Mainly, the legal issue will be “who gets what when/if the game gets sold." Similarly, if you end up asking for help, the first things the help will need to know are Will This Be Sold, and Will I Be Compensated For Helping?

At the point where you are, though, just keep that in mind for later while you work on the game.

By the way, you feel like you need help with art/music creating for your game you can hire a freelancer. Yes, it might be an issue to explain what exactly should be done, but if you have this strict vision of how it should looks/sounds they are a good choice.