Hi!
I've been currently toying with the idea of creating new Units with clunky movement (e.g. shield Wall movement):
What do you think about Units with different geometrics such as a Square instead of circle/Disk? Such a Unit would only be allowed to flip over the straight borders of the square and would thus be hindered in movement without the need for lengthy new rules (imagine the moves of a triangle Disk...).
Of course it would not be pure "Disk"-wars anymore. ;-)