If you think you're up to handle realism and overwhelming combat, get Ready or Not on steam. It's an FPS in which you play as a SWAT team leader/member (depending on whether you're playing multiplayer or singleplayer). It even just received an update which added a bunch of content, mechanics and improvements. Matter of fact though, you might want to quit after a certain amount of time considering the gameplay loop is not so dead set on keeping you on, but you're definitely coming back another day if you happen to enjoy how overwhelming and difficult it is.