If you've been hiding under a very un-tactical rock then this will be news to you, the excellent top down tactical entry game,
Doorkickers from Killhouse games, after almost 2 years of development/early access, and beta(s), has been officially released!
You can go the Steam route which also supports Steam's mod/mission support thingy, or be off the grid with a DRM free GoG version.
Check the site for more info, including screens and videos:
http://inthekillhouse.com/https://www.youtube.com/channel/UCPt3aY19O7vMpz_2t5NFElQI've been a supporter and a player of this game since early announcement... and it's been AWESOME, and that was just with the featureless alpha and beta, final game has so much more, really an incredible job done by the development team.
And if you use me as a operative, I better see some real world tactics being used with my in-game avatar! or else.