At its core, Mercenaries is a third-person action game that puts you in the combat boots of one of a trio of hired guns, dispatched to North Korea to try to take down a maniacal general. He decided to stop the machinations of his father, who figured that the best way to go down in the annals of history was to unify the two Koreas once and for all. His son, General Song, wasn't about to let this happen, so he killed the old man, along with a group of high-ranking officials from both countries. Now, it's up to you to take down Song and his men, presented as a series of playing cards, similar to the system used in Iraq.

The Allied Nations, realizing that a North Korea ruled by this megalomaniac would certainly be a threat to the free world, entered part of the country, but they weren't alone. The Chinese have expansions plans, and taking over the smaller country would be relatively easy if the General was out of the picture. The South Koreans, on the other hand, are more worried about the country's sizable nuclear arsenal which is aimed in their direction. Finally, the Russian Mafia, seeing a great opportunity to profit from the inevitable clashes between the factions, set up shop to offer their services to the highest bidder.
As a mercenary, it's your job to make as much money as you can from all of these factions by accepting contracts from them. The mission structure is similar to that found in the Grand Theft Auto series, as you'll see a faction icon on your map indictating that there's a mission available. If you go to the HQ, you'll be able to talk to the group's leader, who will give you some background about the mission, how much money you can make, as well as what must be done to complete it successfully. Some contracts also have secondary objectives that can be completed to earn some extra cash.
Overall, the missions show quite a bit of variety, and most of them require you to think creatively. At the beginning, you'll be given some tools, from vehicles to weapons, that might help you along your way, but it's your choice as to how you use them. In this way, the game is wide-open, as you can handle things with brute force or with finesse, from afar or up close and personal. The contracts are all very enjoyable, and challenging enough to keep things interesting throughout.