This will happen if it's a card that consumes resources and you don't have enough of that resource. Example: if the card says -5 wood/sec, the card will pop off of the grid once you no longer have 5 wood to consume.
the red circle thing you have to move first before you can move the actual block are annoying. I can see their point when they block a path of 2 or more blocks to be moved at once or be flown through etc. still it is more of a hinderance than fun.
the prequesites for the global merge are not consistent. it say 15 + companies needed but in the same sentence all company upgrades needed, which requires at least 23 companies to do so..
not always logical why a block should move or not. Exactly the same (in lvlv-) setting in different levels could lead to different blocks moving. Confuses my brain hard.
Hello! You can change controls in settings menu. Thansk for playing.