|screen shot of one of my less than decent games|
Every time you shift the tiles, a new tile appears in one of the open spots. Usually it is a 2, but sometimes it is a 4 instead. When the board gets tight, you should really pay attention to how the tiles will shift so that a 2 is always going to be open. Otherwise, your empty slots will start filling up and you lose flexibility and eventually the game.
I played this game during my drying time for my glam thrift store lamp project. Usually I cannot stand waiting for things to dry, but I had to set a timer so I would not forget while playing this game! The game is super addicting for me, so I almost feel irresponsible for recommending it to our readers. 2084 is a true time suck, but you can think about it as brain exercise. That will make us all feel better after spending too many hours to count playing.