Avengers: Age Of Ultron - 11 Ways It Was Almost Completely Different
2. Ultron Was Originally Built By The Government
Before Whedon and his writing team reinvented Ultron's origin story and had him created by Tony Stark and Bruce Banner, they actually had an early draft of the script that was closer to the comic source.
While it's not clear whether they would have had Hank Pym create him, that draft had Ultron brought to life by the US government to replace the Avengers. Inevitably - because nobody ever makes security systems that don't have killer back-door systems - Ultron went rogue and the Avengers were forced to reteam up to bring him down.
Ultimately, it's Stark's desire to replace the Avengers (or improve on their human failings) that sees Ultron created.
Would It Have Worked?
The closer relationship between Tony Stark as creator and Ultron as "monster" actually allowed for more of the Pinocchio/Frankenstein/Jesus imagery that was so key to understanding the relationship (and Ultron's compulsion to create Vision). And it sort of explains why Ultron's personality resembles Stark's (though maybe don't pick at that too much).
There's some regret that Hank Pym wasn't brought in at all, but Ant-Man is hot on the tail of Ultron, so it's not like fans will need too much reminding that he exists. It's just a shame, as it makes it seem like Marvel aren't as keen on tying Ant-Man to the wider MCU as they should be.