Green and red blocks sit / lie on blue blocks or ingots or bars.
These bars have to be destroyed as fingertip that the green blocks remain and fall down the red blocks.
Green - good red - nasty! The game is of course more difficult and tricky with increasing Games history. The blocks may sometimes be circles. But always it is important to secure the green and to promote the red into the virtual afterlife.
As a free app definitely a "buy" recommendation for everyone who wants to make love in between times tricky, but also fast games. One has but depending progresses the game, pretty much prove thinking skills. Always nice to remember: Keep green on the screen!