Marvel has done a great job with the What If...? concept. The alternates realities from the comics have resonated, including stories from the Marvel Zombies world. Throw in provocative stories such as What If Spider-Man Had Joined the Fantastic Four? and What If... The Hulk Killed Wolverine?, it's easy to see why the idea has been a hit since it was created in the '70s.
Source：https://www.cbr.com/events-for-a-star-wars-what-if/
