So many little things I like about Insurgency. Most of all the immersion. Radio chatter sound FX, ambient noise, gun fire and bullet ricochet, smoke and grenade shrapnel splashes. Despite 1998 graphics the in-game immersion feels believable. Night battles I don't like too much coz I don't do well there but feels the best to be in a firefight in. When I'm sucking I just run around and enjoy the atmosphere. Also, randoms in Insurgency are probably the chattiest bunch of gamers on Steam.
Of all the shooter games I've played in the past, this one I have never come to hate. It's casual, no elitist attitude in general, very little toxicity (comparatively), 1 bullet can kill you, slow paced but high requirement for accuracy. Only downside to this game are the weapons.
I've always felt, if only Insurgency had Contract Wars weapons - this game would be my all time classic.