Came across a very positive retrospective of Marathon Infinity dating from 2007.
It starts out...
If Marathon was an earnest indie film and its sequel was the crown-pleasing Hollywood smash, the conclusion of the trilogy -- Marathon: Infinity -- was a daring arthouse creation designed to challenge and mystify its audience.
Great read... you can find it at
From that page you will also be able to find retrospectives of Marathon and Marathon 2.