Cloudflare is a decent service, with really good security. Plus, with their tunnelling feature, they’re helping to keep you private. If you just pointed your A record to your IP, that’d be visible to everyone. Instead, your A record is just visible to Cloudflare. Plus it’s handy if you’re using them to forward a bunch of services onto the net. Not to mention all the other security features you can use. DNS records by design, are not private.
Having it open source, does not make it good. I think I’d prioritise making it fun, try to.make a profit, and then open sourcing it. I don’t think having it open source will help you sell copies… you might sell less. Make your money first, have a feasible business strategy, so you don’t go bust. Then try to keep the game alive vis open sourcing it.