Well it has a system. But with no explanation it is pretty hard to understand. I needed 5 rounds until i survived longer then just 1 minute. Also the problem that i couldnt scale the window or the top bar would block the view made it so hard for me to even see the resource icons that it straped down to a guesswork.
The drag and drop works good. and the Tetris like block patterns make it also nice to try and reach the perfect match over the whole zone.
It is just hard to enjoy with these fundamental technical problems.