The success did not materialise and Square Enix's big bet Marvel's Avengers, which was filled to the brim with microtransactions and live service elements, fell flat when it was launched three years ago. No wonder they decided to end the project prematurely and after being sold at a heavily reduced price for a long time, as the game has now been officially removed from all digital stores.
The 30th of September was your last opportunity to get a digital copy of the game, and should you want to look up the game today, physical discs are the only way to go. But then there is also the question of how long the servers will be allowed to run, and the risk is imminent that they will be shut down in the not too distant future.
Do you play Marvel's Avengers, and why do you think the game never became very popular?