There was a sequel to the book called "Fall of Colossus", but no film was ever made of it.
Here is a review of the sequel.
In the 22nd century, mankind lives under a semi-benevolent dictatorship under which even individual character is more a matter of machine control than personal choice. Unfortunately, this has less to do with the premise of "Colossus" trilogy (which could have been interesting) than the skills used to write each at least this entry in it. Though a compelling subject, "Fall of Colossus" isn't imaginative enough to raise the tension it suggests. (Fall is the second entry of the trilogy; I never read the first book, and have yet to get into the "Colossus and the Crab".) In "Fall", the supercomputer "Colossus" has been in power for years. Still wielding power over mankind through its hold on man's nuclear weapons, much of the world has settled into an existence not radically different from our own. Nukes aside, Colossus also rules through a repressive quasi-religious cabal, "The Sect", that describes the machine as a god, with Forbin as its prophet. Under the Machine, justice is swift, but also scrupulously honest (the computer is aware that scientists close to running Colossus are also members of the anti-machine "Fellowship", but holds off for want of conclusive proof). Life is strictly regulated, but hardly an Orwellian-style police state. However, there are the ESC's - hidden laboratories in which Colossus precisely and painfully studies the limits of man's emotions by subjecting ordinary men and women to tests of varying degrees of cruelty. The ESC's aside, the machine also picks at the brain of its creator - Father Forbin himself. What the machine is unaware of is the nature of an even more dangerous threat to its existence - Martians. As Colossus submits orders for an even larger extension of itself, Forbin's wife receives messages over the radio - voices claiming to come from Mars offer their help in ending the Machine's reign over mankind. The Martians first enlist Dr. Blake, a key Colossus functionary, and Cleo Forbin - Forbin's wife. When the machine outmaneuvers both Blake and Mrs. Forbin, only Father Forbin himself can complete the Martian plan. However, Forbin has his own sense of loyalty to the machine. When the machine punishes Forbin's wife, that loyalty may be stretched too far.
Unfortunately, "Fall" is a slim book, and nothing therein delves into the baggage created by the concept of the supercomputer. The characters have no depth at all - both Sect and Fellowship have their own greed, with the machine being a convenient focus for them to lash out at each other. Though brilliant, none of the characters privy to the Martians' plan take the time to consider the wisdom of acting on behalf of Mars. Worst of all, the Colossus-ruled world really isn't that scary or different than our own - with corporations using computers to sell us stuff or dictate our future. Not a whole lot of imagination is at work in this skim-worthy tome. The Sect seems entirely useless - being around if only to make themselves unlikable. The Fellowship barely registers at all - seeming composed of only Cleo Forbin & Blake. (Even the names seem wrong - almost randomly chosen.) Worst of all, for a story that pits man against machine, "Fall" lacks any subtext, any of that unquantifiable stream of ideas that separates pristine AI from the flawed natural version.
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It sounds so dim that I cannot comprehend how they avoided a sequel.
There was somehow a sequel to Weekend with Bernie (in which two dolts schlep a dead guy about) and TWO sequels to "Hardbodies", after all.
