The gameplay concept is great, but it's not just for me and feels dated. Here are few points I'd like to mention,
1. The only guides are "How To Play" on the main menu and the "i" icon on Campaign which shows some information if you hover over it.
2. The control feels clunky, especially when interacting with the door. I also was unable to find a way to control and move multiple troops at same time.
3. For better or worse, the difficulty between official missions can be very varied. For example, I managed to finish mission 20 in one try just by making my troops walk around and do manual branch/kick the door as needed.

P.S. This is a neutral review, but I chose 'positive' considering SteamDB showed this game had five 75% discounts in the past 12 months.

I really like this game. It's very reminiscent of the old mobile game "Breach and Clear", which was abandoned prolly over a decade ago. My only criticism is that the operators move very slow. Room Entry Tactics rely on Speed, Surprise, and Violence of Action in order to be successful. The only thing I see is Violence of Action.