Gears of War 2

The 5 Flashback maps you need to play on are:

Canals
Gridlock
Mansion
Subway
Tyro Station

It is possible to gain this achievement solo in local multiplayer. Simply set up a local multiplayer match (do not select Wingman) against 1 bot. Warzone is probably the fastest when setting it to be a 1 kill win.

After selecting the correct map pick your character and weapon and start the match.

Hunt down your oponent and kill him to win the match.

Once you win the game just set up another match but on the next map :)

After winning the match on the final Flashback map you will gain the achievement.

For this achievement you need to win a match on each of the 5 new maps from the Flashback Map Pack DLC.

Here's a list of the 5 maps you need to win a game on for the achievement, use it to keep track of which maps you win on;
• Canals
• Gridlock
• Mansion
• Subway
• Tyro Station

Now the achievement is left entirely open as this can be obtained by winning a match in any mode (except wingman), so while you have the option of playing online in a ranked/social match and working toward this achievement casually you can also choose to get this achievement out the way by playing a local game with 2 controllers.

The quickest way to get this achievement is to set up a local game, set the game type to Warzone, set the round limit to 1 and work your way through the maps while killing the second player, this way you have absolutely no threat to contend with as the second player won't do anything unless you make him.

You can use this method any way that you want, you can set up a match with you facing off against a team of bots if you want, it's entirely up to you, I've just outlined the easiest and fastest method that I know of.