It's a shame I didn't reviewed this game earlier, cause Door Kickers definitely should be recommended :)
About year ago(30.Sep.2013) I got Door Kickers as Early Access game and then I wrote:
"Even for Alpha/Early Access Door Kickers looks so promising and fun.
What game lacks for now(from my point of view) - non-lethal weapons, handcuffing and negotiating, by "negotiating" I mean - trying to force suspects to surrender and if something goes wrong you're free to shoot.
In SWAT-2 before entry you have to negotiate with suspects by "throwing phone" or calling to the building directly - this gave you time to plan your entry or even trade out hostages.
After that you could go dynamic or stealth according to situation, but all time from start to the end you advancing - slow or fast.
But the main feature was that all time you was trying to take all suspects alive, save hostages and try to avoid losing officers.
If you will add this-like flavor(no need to copy, just give it flavor as you see it), damn I promise that I'll buy second copy @ Steam :D"
After a year of development, Dev Team added all these features, except "negotiating", - but that's ok for me.
Without this feature Door Kickers plays like R6 and that's not bad at all.
Besides, they have added lot of new features:
New modes like "Drug busting", "Hostage Rescue" and etc.
Tons of maps.
Three amazing campaigns.
Lot of toys for your Good Guys Team.
And many, many more... :)
Anyway, would definetly recommend Door Kickers for anyone who played and liked Rainbow 6(R6: Rogue Spear and R6: Raven Shield) and/or SWAT 2, 3 & 4.