In the news, the topic of "We are compelled to stop free access" wrote that, quote: "We are in great necessity of financial support to keep developing the game and enhance our servers." As you also wrote, "We did not expect a dry and a big wave of new users.", Then you may want to present the game on your website kickstarter.com, thanks to which you can perform a fundraiser for smooth continuation of the project and the opening of a free test server.
The game has a very high potential, and thanks to this site, you can also estimate its popularity not only itself but also its value to a potential customer / player.
But this is just my little suggestion.
I'm sorry for the mistakes, I use google translator