Perhaps more technically Stealth then Tactical Realism, the Death To Spies games had more realistic, open world 'sandbox' and emergent game play than anything else in the stealth genre -- then (2007) or since in my opinion, and bore more resemblance to Hidden & Dangerous 2 for aesthetics, atmosphere, depth of interactive features, realism, and difficult game-play.
Death To Spies 3 is making a second attempt at crowd funding here on KickStarter, and there's a good RPS article here that gives a synopsis of some of the history and direction taken. Although I can't speak to this latest incarnation of the series; I can offer that the other two games like OGR treats it's audience as adults, if not even more so with implicit rather then explicit narrative, and deeper game design.
As an OGR Fan I find the Cold War setting they're running with much more compelling then the run-down we're seeing in most recent games depicting contemporary warfare and absurdist versions there of. If you enjoyed the original DTS games, pitch some pennies in Haggard Games direction -- they're hard working, don't seem greedy in the least considering how little they're looking for, and this appears to be a real labor of love.