Is my Diffy game degenerate?
Pyth, 6 bytes

suaV+e


Test suite

This program is very suave. 0 (falsy) means all zeroes, anything else (truthy) means not all zeroes.

How it works:

suaV+e
suaV+eGGGQ    Variable introduction.
 u       Q    Apply the following function repeatedly to its previous result,
              starting with the input. Stop when a value occurs which has
              occurred before.
  aV          Take the absolute differences between elements at the same indices of
        G     The previous list and
    +eGG      The previous list with its last element prepended.
s             The repeated value is returned. Sum its entries. This is zero (falsy)
              if and only if the entries are all zero.