Avengers: Age of Ultron isn’t the greatest MCU entry, nor is it the worst; instead, it arguably exists in the same pocket of space as Ant-Man and the original Thor – a fun movie, for sure, but not one you’d rush to see again.
For Age of Ultron, that mostly comes down to James Spader’s mechanized villain, who felt totally uninspired when compared to the tempestuous unpredictability of Tom Hiddleston’s Loki, who ruled over The Avengers with an iron fist and a very pointy helmet.
A by-product of Tony Stark’s ingenuity, Ultron played on the whole ‘Pinnochio’ trope ad nauseam (“there are no strings on me”), culminating in the moment when Earth’s Mightiest Heroes banded together to stop Ultron in Sokovia. The collateral damage would ultimately spawn the Sokovia Accords and, through time, Captain America: Civil War, but at least based on some concept art over on Reddit, the Avengers almost came up against a skyscraper-sized Mega Ultron, as seen below.
The being’s anatomy looks to be made up of countless Ultron sentries, combing to create an insurmountable goliath capable of swatting away the Incredible Hulk without breaking its stride. Thankfully, Joss Whedon and his creative team ultimately kept things relatively grounded during the Age of Ultron finale, which no doubt allowed for more character moments between Earth’s Mightiest Heroes.
Besides, Avengers: Age of Ultron was already a CG-laden spectacle to begin with; introducing an immense robot monster into the fray would’ve only muddied the waters. And it should be noted that while this concept art is undoubtedly impressive, it doesn’t necessarily mean that Whedon was on the verge of ‘going big’ for the sequel’s third act.