You can absolutely do it, but I'd encourage you to write-up a sketch of a business plan before you sink a lot of energy into the venture. Why? Because theme parks are a niche software market in an industry with huge aversion to risk (and how risky is a one-person sw solution). Do you have connections or authoritative experience to sell into this market? Do you have commitments to spouse, kids, friends, or self that are willing to give up most or all of their time with you?
During the course of completing a quick-n-dirty business plan you may expose other markets you could sell into (guiding your sw toward a more general code base with industry-specific modules), reveal weaknesses in selling strategy that guides you over the subsequent months to network through linkedin to people that can provide connections.
The point is not to discourage you but to force you to think through things you might have overlooked (like how you would deploy & train the software for your first sale, in SomeRandomTown1000MilesAway, which pays Net 90, while holding down the other job).