Heroes of the Storm

Heroes of the Storm is a MOBA/ARTS game developed by Blizzard Entertainment. It contains characters across the breadth of its games, Overwatch included.

Announcers

 * Athena
 * Katya Volskaya

Battlegrounds

 * Hanamura
 * Volskaya Industries

Creeps

 * Mega enforcer
 * Omnic ninja
 * Sentinel
 * Triglav protector

Heroes

 * Ana
 * Genji
 * D.Va
 * Hanzo
 * Junkrat
 * Lúcio
 * Mei
 * Snowball
 * Reaper (as a skin for Valla)
 * Reinhardt (as a skin for Johanna)
 * Roadhog (as a skin for Stiches)
 * Soldier: 76 (as a skin for Raynor)
 * Tracer
 * Widowmaker (as a skin for Nova, and shoulder-pad art for Tychus)
 * Zarya

Mounts

 * Orochi Hovercycle
 * Busan Police Hovercycle

Other

 * Pachimari

Nexus Challenge
The Nexus Challenge took place between November 15, 2016 and January 4, 2017. During this time, playing at least 15 games of Heroes of the Storm with a friend rewarded players with Zarya and an Oni Genji portrait. Players who also have Overwatch received the Oni Genji skin, Oni Genji player icon, and Oni Genji spray.

Nexus Challenge 2.0
The second round of The Nexus Challenge is closely tied with Overwatch.

The rewards (in both games) are the following:

Week 1

Play 5 games with a Friend (in Vs AI, Quick Match, Unranked, or Ranked) to receive the following rewards: Week 2
 * Overwatch
 * Oni Genji Skin
 * Oni Genji Icon
 * Oni Genji Spray
 * Heroes of the Storm
 * Oni Genji Portrait
 * Oni Genji Spray
 * Oni Genji Banner
 * Orochi Hovercycle Mount

Play 5 games with a Friend (in Quick Match, Unranked, or Ranked) to receive the following rewards: Week 3
 * Overwatch
 * Officer D.Va Skin
 * Heroes of the Storm
 * Busan Police Hovercycle

Play 5 games with a Friend (in Quick Match, Unranked, or Ranked) to receive the following rewards: Week 4
 * Overwatch
 * Officer D.Va Icon
 * Officer D.Va Spray
 * Heroes of the Storm
 * Officer D.Va Portrait
 * Officer D.Va Spray
 * Officer D.Va Banner
 * Overwatch Nexagon Mount

Play 5 games with a Friend (in Quick Match, Unranked, or Ranked) to receive the following rewards:
 * Overwatch
 * 10 Loot Boxes
 * Heroes of the Storm
 * 10 Loot Chests

Cosmetics

 * Skins