Differences between the Grand Theft Auto series and Mercenaries include:
- No auto-aim, rather two-stick FPS style shooting
- Setting is war rather than a city
- This being a war, mostly anywhere you go you have a risk of being shot at if you are not on good terms with a certain faction
- You can only carry two weapons and 6 of each type of grenade at once, which you can see on your back.
- Significantly less blood and profanity.
Similarities between the two include:
- Like in GTA 2, it is advisable to keep all of the factions on your good side. If they do get on your bad side, you might have to upset another faction to get them back, or pay them a nice hefty bribe to make them like you again.
- You are able to take basically every single vehicle you lay eyes on. (Russian delivery copter not available for taking)
In the game, you are assigned to verify (either kill and photograph or hadcuff and extract via helicopter) the fictional "Deck of 52" (Based on the Deck of 52 from the Gulf War) which contains General Song(ace of spades) and 51 of his accomplices. Along the way, you also meet with other factions (Allies, the Chinese, The Russian Mafia, the South Koreans) with different business in the country who are willing to pay you if you help them. The entire game is a balancing act between the factions.
It is the near future. The presedent of North Korea, Choi Kim, has begun to show signs of peace towards South Korea. The night before the treaty to end the long lasting war between the two countries is to be discussed, President Kim is assassinated by his son, General Choi Song. A few weeks later, a vessel transporting WMD's is discovered by Allied forces adrift in the middle of the ocean. It is discovered that these and many other shipments were destined for North Korea, and so the Allied Nations decides to step in and stop General Song.