Hey Renato, good job you did here, but I would honestly don't sell and I'll definitely don't buy.
See, I've been wandering on HE a couple of hours yesterday, and your project seems to have some serious execution flaws (bad ui, downtimes, social based income, etc).
Nothing serious for a side project but these are definite blockers if you ask for a 50k something.
Not mentionning the stack: slackware (honestly?), php and python (why two langages?), no framework. The last one could be the main reason you are struggling to keep it afloat, and that at least throws a big red flag: "I'm gonna head troubles if I'm gonna buy".
And the business side doesn't seems to be worth it.
My 2 cents on selling/buying webapps : I would be keen on paying 10K on a website-based business with 10 long-time customers paying 100$ each month.
That's not the kind of deal you seems to be after, but I think this is somehow the standard for serious buyers on the market.
Why so low you may ask? Because if I understand your project to the point I could buy it, then that means I can replicate your little business.
I'm only buying time, and I think it would take ~10 months to build that webapp and gather some ~10 customers (maybe yours, now I know your flaws...).
And that means buying a strong problem solving webapp, not a niche online game.
If the webapp is very well executed then I would maybe push to 15K per 10 recurring customers, not more.
And I don't care the market size: it's for the potential 100 recurring customers that I would be in, not for the seldom social viralisation peak with an only 1 or 2% conversion.
In a nutshell: don't loose your time trying too hard to sell it.
If it sells then congrats, but you should spend your time fixing the UI to keep your players onboard, writing a great FAQ that handle the tickets, and boosting your infra so you that you're not needed around when it collapse.
Because after that you're done: let it live alone and enjoy your 1000$/month.
Based on my experience there's little chance you'll reproduce that for the years coming.
But that's still a good feat for your age and experience, kuddos and congrats to you ;)