Hidden is the eleventh Special Ops level in Call of Duty: Modern Warfare 2 and it is in the first in the Charlie tier of operations. The objective is to reach the extraction point, silently eliminating any enemies you find or avoiding them altogether along the way.
Hidden takes place in Chernobyl (after the disaster), and the player must navigate their way to the extraction point, which is where the level "All Ghillied Up" began, from the shipping container area, passing through heavily infested radiated areas. The player begins the level with an Intervention, which is suppressed, as well as a silenced USP .45 with Tactical Knife. There are silenced weapons at the start that are able to be picked up as well: the MP5KSD, the Mini-Uzi, the M1014, and the Striker. The game keeps track of how long the player takes to reach the extraction point and is also ranked on how efficiently they kill each individual enemy; the system used includes "Perfect" kills, "Good" kills or "Average" kills. This will not affect the star-based score that the player receives at the end of the mission in any way. The number of stars is based on the difficulty the player completed the mission on, regardless of the type of kills that one accumulated.
Grenades are very useful in taking out the Ghillie snipers. If the player wasn't noticed before throwing the grenade, and a sniper is killed by a grenade, it will still count as a Perfect kill.
Type of enemy/ type of kill
The player must kill a soldier without being noticed
The player has killed a suspicious soldier
The player has killed an aware soldier
The player must kill a sniper without being noticed
When the player picks up an unsuppressed weapon, Soap will give the same explanation on unsuppressed weapons as from the level "Cliffhanger". This also happens in "Acceptable Losses" and "Evasion".
On Hardened and Veteran difficulties there is a sharpshooter in the church's tower. However, his behavior is the same as that of a regular guard, not a ghillie sniper. Furthermore, he is the only marksman armed with a Dragunov.
It is possible to access the city of Pripyat and the rest of "All Ghillied Up" behind the spawn area by jumping on several cars and over a fence. Here, the radiation zones are not hazardous and the player can walk over to the Chernobyl plant although an invisible wall will prevent the player from returning to the map, requiring the player to restart the mission. 
All TVs in the map can be interacted with by using the use button, they will turn on and show a blank RGB Color test screen.
There are 4 TVs across the map, 3 in the main building in Chernobyl, and 1 in a shipping container in the junkyard with the BMPs and Hind helicopters.
In some rare cases the MP5KSD will spawn as the MP5K, its non silenced variation.