Skulls of the Shogun

If you own this game on multiple platforms this achievement is easily boosted solo. (Also possible just using an Xbox or Win8).

You'll need a second XBL account (silver will work if xbox is not being used). Any of the following will work as setup 2 on xbox (if both are gold), 2 on Win8, Xbox & Win8, Win 8 & WP, and Xbox and WP. Load up your primary tag on the device you need the achievement for. Load up your secondary tag on the other device to be used for boosting. On both Xbox and Windows 8 app purchases can be shared between accounts. (See below)

Set up a Skulls Anywhere game, Deathmatch, 2 human players with 1000 starting rice on the map Pink Pursuit (Must be a large or extra large map as small and medium do not have enough rice paddies).

For the first 10-12 turns the boosting player should haunt all the rice paddies (generate infantry as necessary) and then spend all the rice on infantry (do not buy anything else or you won't have enough rice to have 30 men). You can also pick up the two additional monk-like demons. At any time it would be a good idea to wake up the boosting general so that he doesn't gain too much health.
For a couple of the early turns send a primary tag cavalry up and build three archers. I'd advise against killing any enemies until there are more than 30 on screen at once (I couldn't build anymore after 32) and not kill any that are still pulling in rice.
Spend the remaining 18 or so rounds just plowing through them with your five archers, making sure to eat skulls with two archers each turn (otherwise it will take you forever to get through them all).
After both players hit round 31 take out the general (as long as all the other enemies are down).
Achievement will pop at the win screen.

Additional info: After eliminating about 10 enemies I went ahead and had the boosting account finish out the rice storage with another 5 guys and I waited until round 32 showed up just to be on the safe side.

If you download a game on Xbox with your primary tag, your secondary tag can also play it (but it will require a gold account to play online).
To share app purchases in Windows 8 requires you to create another user account with your boosting email address and to go to the store and change the store account login to whichever one you used to buy the game on Windows 8. For more info see this link. http://winsupersite.com/windows-8/windows-8-tip-share-apps-b...
The WP cannot be used to boost as the game would need to be repurchased. I would recommend avoiding the WP when working on this, if possible, except to finish off the last few rounds as I've seen many games where the sync just got all messed up.

Commentary: Yes you could get two people together to do this, but many may prefer to do it solo since it will take just as long either way. FYI: Sending the turn information on Win8 takes about 30 seconds compared to about 5 with both XB and WP.

I haven't yet gotten this on 360 but you can see that I have it on Win8 with both 360 and WP to follow soon.

Please comment with any ideas or criticism.

This seems to be fairly glitchy. Kills and rounds don't seem to be consistent between players.

It might show to me I have 35 kills at the end of a match, but to another player, it could show I only had 12.
Took us three tries to get our third person this achievement, and we found it's best for the person going for this achievement to host the match, as when he did, the kills were shown as the same to all of us.

So make sure you are the host when you go for this achievement, and hopefully you won't have any issues.

As above, it's a heck of a lot easier and quicker if you have a second Xbox Account on another device.

The way I did this was as follows:

Created a 1v1 Deathmatch game and set the initial rice to 1000
I created about 5 archers with my main account and got the second account to produce nothing but Swordsmen and Calvary.
Just keep killing the Swordsmen and Calvary with your archers (make sure you turn them into Demons by eating the Skulls as this will give them to attacks per turn).
I found that when I got to about round 25 I had the required amount of kills.
Just keep ending the turns quickly until your at round 31 (I did 1 extra to play it safe)

...NOW HERE IS THE EASY WAY SO YOU DO NOT HAVE TO GRIND THREE PLATFORMS...

Load up your Final Round (The round where you will do the final blow on the enemy general) on all 3 main devices at once. Now complete the mission on each device at the same time and the achievement will pop across the 3 devices for you :).