Unstackable is one of the Physics Games that you can play on UGameZone.com for free. Have you ever impressed yourself with that instant response when you catch a falling glass without letting it break? Click on the objects on the bottom of the shelf to remove them without letting the top crate fall on the floor. Aim to land the top crate safely onto the shelf. Respond as fast as you can to deal with the domino effect as a result of one item you removed from the stack. Each level of the shelves gets increasingly difficult to unstack. Can you unstack the unstackable? Have fun in this puzzle game!