Hello. I'd like to suggest a lot of things. Many of them are featured in Unreal Tournament modification called Infiltration 2.9. I played the Community Edition with Bonus Pack, Weapons Pack and stuff that doesn't really matter. SO, to the main thing: Infiltration aimed (the game is long dead) to be as realistic as possible. No, it's not about graphical realism, it's about the physics, weapons, nades, damage, camouflages, player and weapon models, gameplay realism. Especially the weapons and nades. Let me just link you to the site that will describe the game and all of it's features. The guy who wrote that is called Dslyecxi and he is really famous for being god in Arma 2 and 3. Please read it, because it is REALLY WORTH IT.
http://dslyecxi.com/botg_infiltration.html
Pay attention to how the nades are thrown, how they roll, how the weapons are aimed, their ironsights, different movement speeds, stamina, weapon and ammo bulk, flashlights, scopes, holding breath and everything...
Thank you.
-Chameleon
http://dslyecxi.com/botg_infiltration.html