The main character is an ex sniper named John McAffrey, who got expelled from his sniper squad after a hostage situation went wrong. He becomes a private detective and hires a secretary, Jane Collins. One of his first assignments was rescuing a man held captive at the docks. After he completes this mission he gets a visit from a prominent Mafia figure known as The Don. The Don explains that he was making an example of the man John rescued from the docks, that he was a drug dealer and that he, the Don, will not abide by drug dealers.
He continues to say that he will pay John if he starts working for him, and that he really dosen't have a choice. Faced with financial trouble John reluctantly accepts this business offer.
He then proceeds to do a number of small time jobs for the Don that leads him on the trail of a new drug that appeared on the market ,,Cold Zero''. The don insists that the drug must be destroyed so John starts searching for the source of the drug, this leads him to Yapala in Guatemala where the drug baron known as Martinez operates.
Cold Zero: No Mercy is a third person shooter, the weapons can be divided into several groups based on their weapon type such as:
- Melee weapons
- Submachine guns
Also they can be divided by the manufacturer, either to west weapons that are produced in the west or east weapons which are produced in Russia mostly.
Each weapon can have up to 3 accessory slots, silencers, scopes and barrels, each of these accessories has a positive and negative impact on the weapon. Barrels increase the sound the weapon produces but increase its accuracy. Silencers decrease sound level but they also decrease accuracy and damage, scopes increase accuracy.
There are some RPG mechanics withing the game, like an inventory where you can keep all your ammo and weapons. And character progression, John will gain experience for every enemy he kills and every door he unlocks, once he gains enough experience points he gains skill points, 500 experience points are needed for a new level and each level the player gains 5 skill points he can distribute amongst different aspects.
Strength - used to determine how much items John can carry.
Fighting - damage John inflicts on his enemies in hand to hand combat.
Camouflage - how well John can hide.
Technology - determines the speed of unlocking doors, upgrading weapons by ading accesories and turning on/off power generators.
Close combat - the use of melee weapons
Pistols - the use of pistols and revolvers
Submashine guns - the use of small fully automatic submachine guns
Shotguns - the use of shotguns
Rifles - the use of sniper rifles and assault rifles
To increase any of these aspects you will need skill points, each time you invest a skill point into a skill it increases the number of points need to increase the skill to the next level.
For example to increase a skill to level one you need one point, to increase it to level two, two points so on and so forth up to a maximum of ten levels.
There are other important attributes that change in combat situations.
Life energy - if this runs out John dies.
Condition of bulletproof west - The condition of the bulletproof west you are currently wearing.
Stamina - Determines for how long you can run or sneak.
Visibility - the chance of an enemy spotting you is directly affected by this attribute, having a high camouflage skill or moving to shadowed areas decreases visibility .
Sound level - How much noise John is making, actions like shooting,reloading a weapon or just moving increase the sound level, if an enemy hears you he will become suspicious and will begin searching for you.
The game features stealth mechanics as well as a run and gun option.
During missions a player can kill enemies, silently or guns blazing an loot the corpses. At the end of each mission the player can see how many enemies he knocked out (with melee weapons or fists) how many he killed and how many he left alive. Also at the end of each mission the player can see how many things he found that are scattered among many containers in a level, how much experience John gained and what objectives the player completed.
The Office Area
The office area is a small town where John's office is located, after each mission John returns here. The starting point is his office where you can talk to John's assistant Jane Collins and store gear in a nearby locker. Once you exit the office you can visit several locations.
Eddie's bar - Eddie the proprietor of the bar is an old friend to Johns father,usually he wont have anything useful to say other then ,,John you are becoming like your father more and more each day'' to which John replies ,, I know i shouldnt drink so much''. Eddie also introduces John to a high level arms dealer.
Pawnshop - John can sell any miscellaneous items he finds in missions such as platinum credit cards, diamond rings, gold necklaces. gold rings etc. He can not sell any weapons at the pawn shop nor can he sell any ammo. You can buy some melee weapons like a hatchet or a knife as well as some clothes and medpacks.
Shooting range - John can go into the shooting range to try out the different weapons there.
Gun shop - The gun shop sells a variety of ,,western'' weapons, ie. weapons that are made in Germany,USA,Italy,the UK etc. You can also buy gun accessories that you can attach to your weapons, things like silencers, scopes, and new barrels.
Gun dealer at the docks - Is the man Eddie introduces you to, he sells the eastern weapons, weapons usually manufactured in Russia.
There are also many civilians you can chat to,most of them will respond as ,,i dont know you''.
Once you are ready to start the next mission you can go back to the office and speak to Jane, then proceed to her car and John drives to the mission location.