I've been playing insurgency for a few years now and have been finding exploits/cheats usable in the game for a while now, the 2 most simple ones I can give out are more as party tricks or useful to fool idiots into thinking you're genuinely cheating.

First one is an .AHK script, when opened through .txt you need to change the first and second number variables to the position of your "join spectator" button when you hold tab, what the script is coded to do is when you press your '/' key, it will just click on the button, this is useful because if you throw a C4, IED, grenade or fire an RPG, AT4 or throw a molitov towards your teammates, when you press the '.' key (team select screen) then '/' key to join spectator, the damage will be dealt to them through a different team, and therefor killing them in the process.
Killing teammates though this method will give you the kills, but will give you no score.
This can also be useful for skirmish or push when there is a team left with a weapons cache, if you throw a Molotov onto a cache, then join the spectators team, the cache will blow up regardless of what team you where on prior to throwing it, this will mean in push (because for the game to end it requires the security forces team to blow up the cache) instead the spectators team has taken the objective, and therefor the game becomes a death match only ending when the last player from either team is dead.
The script is as follows:
/::
MouseMove 0,0,0
mouseclick, left
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What you will need to do (avoiding the lines) is paste this code into a .txt file, change the first two X, Y variables to the pixel position of your spectate button, then change the file type to a .ahk, then opening the auto hotkey script will allow you to press '., /' to join spectators team and kill as many of your teammates as you like!


The second trick is a lot less useful and only use able in public games, trying this on a custom server or a server without the name 'official NWI' will IP ban you.
Command is as follows:
bind k "rcon"
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simply putting this into your console, using any key as the bind, will then allow you to levitate, your game freezes at the same time but you can press the key a multiple of times for a longer levitation period, as far as I know this does not work for bugging out objective caps or as a temporary invincibility, as to where you may want to levitate (maybe to evade enemies) is up to you, I've just mostly used it to trip out teammates or levitate off of high areas and seem like I'm floating mid air.