As true a horror game as anything else, really, with a focus on restricting the player's willingness to take action instead of their ability. You certainly can shoot at anything that moves, but success in SWAT 4 is highly dependent on not pulling that trigger when frightened. Enemies in later levels have guns that kill you faster, but the real threat is the paranoia: wandering in near silence, knowing that your time to correctly assess each situation is shorter than ever as the door in front of you suddenly opens, a gun pokes through and you shoot your co-op partner in the head because you didn't realize they had wandered off.

It's the best survival horror of 2005 genuinely a masterpiece, forcing you to meticulously comb through environments where you feel completely foreign, limited to being the second invader on scene in the best of scenarios. The constant pressure to remain vigilant punishes video game instincts you may have acquired elsewhere, where an impulse to shoot for the head can turn an "unauthorized use of force" into "killed a hostage". The praise might sound silly, but all these mechanics only become praiseworthy due to the work done to create atmosphere - it's incredible that you can skip every single briefing in the game and still come away with vivid memories of each level. Trudge slowly through the dark, combing each inch of a hostile environment for evidence as distant, sprinting footsteps remind you how far you are from establishing control.

As much as I'd like to conclude it there, it's a little hard to talk about this game now without considering the existence of Ready or Not, a spiritual successor that modernizes and blends the core SWAT 4 experience with its expansion and several popular mods. I can easily recommend Ready or Not if you just want easy co-op, but taken as a whole I still find SWAT 4 to be the more compelling experience. In moment-to-moment gameplay, Ready or Not skews a little closer towards traditional shooters than I'd like. SWAT 4's guns never feel fully accurate, the player always feels fragile, and each level feels like it existed before you loaded in - Ready or Not misses the mark on each of these, and has a markedly different mood as a result. Try SWAT 4, mod it if you have to, and see if this style of game is your speed. If you like the core gameplay and want more (or you find yourself frustrated by a lack of QOL features / non-Hamachi multiplayer) then it may be worth picking up Ready or Not, but I'd read up on the changes first.