This game I can't really explain on a basic level, save for a few bits. It's pretty obvious this game takes a lot of inspiration from Half-Life 2 in environments and story. Lots of crawl spaces, various puzzles, driving levels, etc. The only detail I took a lot of notice at was the urban environments look very similar to what HL2 was originally planned to be, as there's quite a bit of Art Deco and weather similar to Viktor Antonov's concept art.
On another note, the lighting and character models, including gibbing resemble Doom 3 a little too much. I almost felt like I was playing it at some points. I also hate the rebel leader, how he emphasizes certain points of his phrases, and how most dialogue with him involves me doing grunt work. He does say thank you though, so I guess he isn't all that bad.
Gameplay-wise, this game is ♥♥♥♥ing hard. I'm not even kidding, the AI is designed to kill you very fast like real soldiers if you don't take advantage of time manipulation. It will happen, don't even try to fight soldiers without doing it. The total time of the entire campaign is about 8.5 hours, which is short for single-player. That's probably just me though, I tend to go through SP games very fast.
If you want to get this game, get it on sale or if you don't care about sales, that's okay. It's worth it.