Age of Empires II: Definitive Edition

One of the things that helped me most on getting this achievement was the usage of pause (F3 or pause/break button on your keyboard). It gives you infinite time to micromanage your troops.

First I'd suggest resigning and looking at the map, and memorising the spots where you can use your trebuchets (trebs) without pulling the troops near the castle, whilst facing the least amount of enemies when pathing towards it. It is also good to note where gold mines are located so you can keep your income of gold up ingame.

Send your army to the east to activate yellow, your scout to teal in the west using the small shallows path to activate teal. Apart from that basic stategy is as follows: Build multiple (I had 3) town centers, a lot of houses, a blacksmith and a market and a univerity asap. Start building your economy and build a castle near the first city gate. Start massing trebuchets. Upgrate your infantry (huskarls) and get chemistry for the treb range increase. You can send 1 treb of east to yellow to safely remove a castle (by positioning it to the east of the cliffs near the castle nearest to yellow).

Now it is going to be a rinse and repeat if clearing a path to where your trebs can shoot as safely as possible (some spots will still require some protection), having your trebs destroy it, and moving on to the next spot (DO NOT DESTROY THE BARRACKSES ETC). You will however need to do this running multiple paths simutaniously since you will not be able to make it otherwise (in the end I was destroying 3 castles simutaniously). Managing this is made a lot easier by using the pause button.

As for unit production, keep spamming huskarls and trebuchets. Using a control group (ctrl+ any #) for your barrackes will make unit creation and initial movement easier to manage, and you can add more barrackes to to that group by using shift + same #.

Even using these tactics you do not have much time to spare, I was well in the 29th minute when victory was declared. For reference I had my resource production and first castle up around 10 minutes, and had destroyed the 6th castle around 23m ingame. It took several attempts to get it right, and I do suggest saving at a point when you feel confident you can make it in time. (had saves at 10m, at 23m and at 27m, and I even had to reload from the last one a couple of times)

If you have 3 other friends, you can easily get that one.

Just be sure to be on 2 different team !
After that, wait a few seconds and have all other players resign.

When we tried this, resigning didn't trigger the achievement, so if it's your case too, just use a small map.
Your friends will have to delete all their units / forum except one villager and send it to your forum to be killed.