The Heroes of the Storm PTR will be updated later today to bring the newest hero and map to the Nexus. Overwatch's Genji will be playable on PTR as well as the Hanamura map with its new game play mechanic.
According to HotS devs, Genji plays much as he does in Overwatch. The Hanamura map does not feature an attack-able core similar to Towers of Doom. Instead, teams escort payloads (or stops the other team from doing so) in order to score points to win the match.
Several heroes will also be tweaked including big changes to Uther. Other heroes being updated include Greymane, Cassia, Nazeebo, and Tassadar.
Check out the full Heroes 2.0 PTR patch notes on the Heroes of the Storm site.