Overwatch has started a new seasonal event called "Overwatch Uprising". Taking place before the fall of Overwatch this event takes place on Kings Row during an Omnic uprising. You can read the primer to the event in the most recent comic here. From the looks of the trailer this looks very akin to the Junkenstein's Monster event from Halloween. Here is the teaser for the event.
So there you have it. So you have until May 1st to get your fill of this event, so get to it!. The world could always use more heroes.