Army of Two

This achievement is not too hard. You must finish all 6 original missions in the story mode by yourself. You can beat the game in any difficulty. I would suggest to play the game in Casual difficulty unless your planning on finishing Professional mode by yourself anyway.

The AI partner is not that bad and is well developed. He can act fairly quick, revives you, and has a pretty nice aim. He does not leave you hanging like most games.

You should have no major issues when playing with the AI partner in casual however here are some hints if you are:

- Take your time. Take cover as much as possible and conserve ammo. You more distance you have the better. Sniping is a great way to play in more open areas. Don't rush out and progress until you have cleared the area out first.

- Work with your AI partner not against him. Cover him when he needs it. Try not to get into areas where your taking on allot of fire, you may need to do some reviving and heavy fire makes that very hard.

- The maxed out Dao-X kills most enemies with 2 shots and also knocks down even heavy armored guards at mid to close range.