There is also an official app [1] that you can use to photograph and track the mosaics you encounter. It also confirms if the design is indeed done by Invader.

I'm not competing on the leaderboard, but it's still a fun incentive to go instreets I don't usually go through to see if there is a design I haven't encountered yet.

[1] https://www.space-invaders.com/flashinvaders/