Earth fragments
Earth has been long abandoned due to its toxic atmosphere.
Dog Days
Dog Days was a summer-themed Tactical Alert in August of 2019.
Long Shadow
Long Shadow was a Tactical Alert in late 2016 that saw the return of the Nightwatch Corps, last seen in Project Undermine.
One Thousand Cuts
The Tactical Alert One Thousand Cuts appeared in Hotfix 18.5.6. This was a series of new missions that appeared on Thursday and lasted until Monday.
Project Undermine
Project Undermine was a Tactical Alert that saw the introduction of the Nightwatch Corps, as well as another run-in with the thief Maroo.
Emergency Exit
The Emergency Exit Tactical Alert was a special Alert mission where the Tenno protected two Bailiffs who were planning to defect from the Grineer.
Den of Kubrow
Den of Kubrow was a Tactical Alert in May of 2015, involving enhanced vampiric kubrow.
Ogma Elite
The Ogma Elite Tactical Alert was an Archwing mission available from 04 March 2015 to 09 March.
Phoenix Intercept
The Phoenix Intercept Tactical Alert was a series of missions that was available from 25 February 2015 to 03 March.
Fleet Footed
Fleet Footed was one of the Tactical Alerts running during December 2014, involving Mobile Defence missions to intercept enemy broadcasts.