This CSS game was just the first of four stages, but it had a prize of 0.005 BTC. The next two stages also have addresses with 0.005 BTC, and the last one unlocks the address with 0.125 BTC.
The link to the third stage does not seem to work (https://btc2018.formapi.io/d63c04b...). I get "btc2018.formapi.io’s server IP address could not be found." When visiting a wrong address, I get "Page not found" instead.
Hmm that's strange, it's working fine for me. You could maybe try a different browser, or curl on the command line.
Oh, I've been had :D
Too bad I didn't know about the Dinosaur game in Chrome.