Edition Cuboro, the game-oriented brand of marble run company extraordinaire, Cuboro, came out in 2014 with Cuboro Tricky Ways, based on the block and marble design of the original Cuboro product line.  They came out last year with a less expensive model, Tricky Ways Fasal, which is identical in all ways except for the scale (smaller) and the materials (they used the fascinating wood composite product Fasal, instead of solid beechwood, a lightweight material that is nice to the touch and the eye).

The game itself seems simple -- In Version 1, each player tries in turn to create the longest marble track from a central starting block to an empty end-point using the surface channels on each block.  On each turn, you can move or rotate 3 or 4 blocks to create your track.  But as the empty spots are filled, the options narrow as to where you can direct your track to end.  And, for those who truly want to give their spatial visualization skills a workout, there is the more challenging version in which you can use not just the surface channels of the blocks, but the interior tunnels as well. 

I've played this many times, including some real spankings at the hands of Cuboro inventor Matthias Etter and can only say:  This is one that will have you scratching your head and revving up your intellectual competitive streak.