The game provides the possibility of inviting players to the game with the referral system.
About the essence is that you give a friend a link that you can find in the Ref. System menu:

Friend registers on the project with this link and you will be credited. You can see it there, where the link is. Once your referral reaches 25,000 points in the statistics, you will receive a bonus of 500,000 Dark Matter and Antimatter 10,000.

Recently, whe have added a referral banners that you can place on other sites. This banner redirect to the main page of the game. Banners, as well as regular link contain your unique ID, for which it will enroll you of a referral. -

Here is a window with a list of your referrals: