Crusader Kings III

You can start in 867 as one of the Karling's and slowly scheme, conquer and kill your way to being the only Karling to hold an independent title.

For patch 1.03 - If you want an easy run, start in 1066 as Count Herbert of Vermandois in the Kingdom of France who is the only Karling with a landed title. Now all you need to do is become independent and this can easily be done in less than 20 years.

The first perk you want is Meritocracy in the Stewardship Lifestyle which will allow you to start a scheme against your leige to claim the throne. While the scheme is going ahead you want to specialise in the Intrigue Lifestyle picking up the Kidnap Perk.

Start a Kindap scheme against the King and then go to agents, here you want to bribe every agent you can but make sure the game is paused (this will allow you to add everyone to the scheme and go massively in to debt). Keep going until the King is in your prison and then start or join a Faction for independence and push your Demand. For this one you dont have to start the war before he is in your prison.

The King will most likely tell you no and start a war with you but because he is in your prison you will get a 100% warscore instantly and can enforce your demands and the acheivement is yours.

A straightforward solution for this achievement is to make use of the Crusades mechanic.

Start in 1066 as the Karling Count of Vermandois and get to work fabricating on your neighbours, this will let you conquer them and build up your own strength. You’ll want to aim at creating the Duchy of Valois whilst upgrading your Men-at-Arms, definitely focus on siege weapons for this.

In the meantime get yourself and your brothers married, but DO NOT land your brothers. (N/B: It might take some time for the Crusade to pop and you’ll be playing as your Heir, but this will still work)

Eventually you’ll see the pop up saying the Pope now thinks Crusades are a great idea, wait for him to announce one for Jerusalem, commit to it and choose an unlanded family member as a beneficiary. Once the Crusade starts, call up your troops and make your way to the Holy Land. Best thing to do now is to wait in the sea for everyone else to land so you don’t instantly get stack wiped. Focus on sieging as the AI tends to just wander around chasing enemy armies.

All things being equal you will get the highest contribution to the Crusade and your beneficiary will become King of Jerusalem. Wait for the message box that asks if you want to now play as them and choose “I wonder what kind of King he will be…” and boom, you are now the only independent landed Karling!