One of the few games I tried randomly back at Essen was Cubulus. The halls were almost closing and on my way out I came past the booth of this game. As it was way way down on my list and the booth was already empty I gave it a shot.
Each turn you push one of your balls into a 3x3x3 grid. The goal is to arrange the balls of your color in one of three patterns to win the game:
a square of 4 immediately adjacent balls
a standing square with the corners in the middle of each edge of the same cube face
or a square with the corners in the corners of the same cube face.
When you push in your ball you may use it to push an existing ball further into the grid but not to push one out again.
Being something of tic-tac-toe kind of game Cubulus is not very deep.
I did like the tactile aspect of the game. Unlike tic-tac-toe or connect four you are constantly handling and turning the rubber cube grid to analyze your situation.
Also the ability to push other cubes through the grid gives a nice additional layer of strategy and the option to screw with your opponents a bit.
Finally allowing a third person to play the game is a very nice touch. I usually skip over most 2 player games since I so rarely have the opportunity to play them.
Cubulus is not a game I see myself buying anytime soon but I don't think I'd turn down a few rounds of it either. It's easy, short and fun but simply not a good fit for my usual gaming circles.
I expect this game would however go over quite well as ultra short filler (for late arrivals perhaps), as travel game or with younger kids. It might also be a good camping game since the components are quite large and look rather easy to clean if necessary.