Gears of War 2

As both of the previous guides have mentioned beating bots is an option. However if you want to do this really easily just sign in another account for a second controller, use a local game and then with 0 bots its just the two accounts in the game on different teams. Kill the guest/other account 5 times with no struggle and the win is yours (Plus 5 points for winning the round, assuming you set the kill/points limit at the lowest option=10). Rinse and Repeat on different maps. This is a lot quicker if you can learn the spawn points. Usually after the each kill you just swap spawn points so it stays nice and simple.

- Canals
- Gridlock
- Mansion
- Subway
- Tyro Station

I would suggest using bots however as it isn't as boring, but if you are having trouble beating them this is a good alternative.

The 5 Flashback maps you need to play on are:

- Canals
- Gridlock
- Mansion
- Subway
- Tyro Station

Local (or privite) game
Bots - 9
Bots on Casual
Round score 10
You need at least 2 rounds

Another way to do this is to start a wingman game with 3 bots, round time 2 minutes and victory limit 10. There will be 3 teams, you will be with a bot. And then, nothing is easier than to destroy two teams attacking each other with the army of two (you and your bot). Takes 4 rounds to win the game.

EDIT: The EASIEST way is to get a friend, 8 bots, easy difficulty. We've almost everytime won in the second round.

- Canals
- Gridlock
- Mansion
- Subway
- Tyro Station

This is a simple achievement all you need to do is play on 5 maps and you need to play wingman put on 9 bot and kill them

These are the map:

- Canals
- Gridlock
- Mansion
- Subway
- Tyro Station

Enjoy your achievement and good luck