Listed in ACE magazine as a Firebird re-release from Ariolasoft, we never actually even saw the original game either.
So was it that Think! only got a Spectrum release, and ACE got the C64 format listing as incorrect? Not sure just yet, but it is likely to be a mistake.
The game was an addicitive 6 x 6 grid puzzle game where you could play against a friend or computer. Sadly we never got to do neither.
Do you know anything more about the game?