The fact that Peggy Carter becoming Captain America is just for a Marvel mobile game tie-in and not, say, an ongoing comic book series that lasts 10 years is breaking my heart as much as it's making me want to triumphantly wave the stars and stripes, and I'm not even American. This year marks Captain America's 75th birthday, and aside from the release of Civil War and Marvel Comics turning Steve into a secret Hydra double agent (but not really), the company is celebrating across their swathe of mobile and PC games, with new incarnations of the legendary hero being released for each one.
They range from the mildly boring (teenage-hero-based Avengers Academy gets a World War II Captain America, for example) to the completely terrible (like the Steampunk Captain America 1901 for Avengers Alliance 2), to the downright weird (like Future Flight's Sharon Rogers, the lance-armed daughter of an alternate Steve and Peggy).
Ugh, steampunk Captain America is the worst.
But the best, by a country mile -- by several country miles -- is Puzzle Quest's Peggy, which imagines a scenario in which Steve was assassinated before the super solider project was completed, leaving accomplished field Agent Carter to take his place.
I mean sure it's a character for a gem-matching mobile phone game BUT BLOODY LOOK AT THIS. I want the faux-old-timey radio play. The Netflix miniseries. The comic book. Five dozen action figures (and at least three of them with a 'Lady Liberty Karate Chop' action feature). Get the mad scientists of the world on the phone, because I want to be in the alternate universe where Peggy Carter is the Captain America.
The alternate Captain Americas, including Peggy, are available to acquire through limited-time events in their respective games now. But let's be real, Captain Carter is the only one you should probably go for.