Fable III

After doing the main quest in Mourningwood Fort, it becomes available to buy. It will be around 40,000 Gold (prices vary in each game by a small amount). Buy the Fort, and go back to where you used the mortar during the quest. Press and hold A on the mortar to start the game.

You have to hit 2000 points in one game for the achievement. This may take several tries but it is not very hard.

Here are some tips:
-Listen to Jammy. He will tell you where the enemies are spawning.
-Hitting them as soon as they spawn is what you want because they will spread out pretty quick.
-Aim for large groups. The more you hit, the less time you waste.
-Do not go too far out of your way to hit one or two hollow men. You can hit one on your way to a large group, but only if it does not waste too much time.

-This can be done in co-op as well. It will combine both players scores and may make things easier to unlock the achievement if you are having trouble.

NOTE: Some people have said they hit 2000 exactly and the achievement did not pop. I got it when 2010 was my score. If the achievement continues to not unlock, you may need to beat your highest score if you got 2000+ and it did not unlock.

Just a few more hints that can maybe help you:

- First strike always on left
- Wait to ear where the 2nd group will spawn (often on left)
- Try to kill groups, easier if their not moving yet
- After the 3rd wave, continue in circle
- Always look at the spawning point

Don't forget: if you'll beat 2000+ on solo game you'll get a legendary weapon, in combo, you'll not.

(the video below helped me - not mine)

It took me about five attempts to get this (I got 2,000 on my third attempt but it didn't unlock. I did it eventually with 2,040) and I would say that staying active in moving across the field is most important.

After my first couple of attempts I began to ignore Jammy after the first 30 seconds as Hollow Men are spawning pretty much everywhere. Just sweep the map in a circular manner and try to keep moving, only pausing to blow up groups of three of more.

Obviously if you see a group spawning over an area you've just been over, go back, but then keep on circling. Speed is the key!

This can also be done in co-op I done this with a friend on our first try and we got about 1200 points each and a total score of 2400 tand we got the achievement

Yeah so after a dozen tries of what seemed like me never missing a group and having a best score of 1940, I played with a co-op and unlocked it on the first try with a combined score of 2720. I'm pretty sure this achievement was designed to be won by a single player, but the best possible one-man score cant be much more than 2050-2100

I got this achievement after about 8 tries solo and noticed that spawning is somewhat random. In some attempts you get more groups respawning. Because of this, even if I was doing basically in the same manner, my scores varied from 1700 to 2000. I also tried to kill off an entire group. If you miss one or two, kill them as well before moving on. It may help accelerate respawning (not confirmed). During final seconds (20 or so), hollow men spawn everywhere and you should be able to nail a few large groups (very crucial).
Just keep trying and you will get it eventually. My first attempt was 1400 :)

The achievement description is a lie!
It isn’t enough to get 2,000 points, you must BEAT 2,000 points. This means at least 2,010.

littlejay x360a points this out in his final paragraph, but I believe when an achievement’s description is misleading, it deserves to be shouted loud and clear. Another caveat is, you must attain 2,010 with an unknown amount of time (1-3 seconds?) remaining on the clock -- people have reported that the achievement will not pop if you hit 2,010 within the final second.

As others have pointed out, the achievement is more easily obtained in co-op, where scores are combined. But if you want the Legendary Weapon reward, you must score 2,000 solo. 2,000 points on the nose is enough to get you the weapon, but not enough for the achievement. I know because I did exactly that: I hit 2,000 within the final second, got the legendary weapon but did not get the achievement.

Something to keep in mind when going for the achievement and/or legendary weapon: Two other legendary weapons have upgrades that are tied to the mortar game. If you own these weapons, have one of them equipped when you play the mortar game. 2,000 points on the nose is enough to unlock their upgrades. They are the Swift Irregular (rifle) and Simmon’s Shotgun.

Good luck!

I got this achievement while playing it in co-op and it seemed to give me more time in co-op mode than it did in single player mode as I got over 2,000 points by myself in the co-op and in the single player I'm lucky to score 1,630. thre person I played the co-op with scored less than 1,000 and she got the acheivement as well.