Playing Crusader Kings 2 and got destroyed multiple times by big bullying empires and kingdoms like the Norse and England, I thought it was almost impossible to play a small state. Then I started playing a small state in Wales formed the Kingdom of Wales. I had some of my dynasty in Scotland from political marriages and fought a war to obtain the claim. I won and the new hardest part of game comes where I had to keep my vassals in line, I quickly found out some vassals hated me way to much and I'm pretty sure I assassinated at least 60 of my vassals because there opinions were so low. I slowly took land from Ireland because I was much stronger and couldn't get my heir into inheritence. Then I married some of my kids into Galicia for the claim on the kingdom, and assassinated the King and all of his children and siblings. At this point I was King of Scotland and Wales and I overpowered Galicia easily with brute force and now I have a claim on the Kingdom of Castilles and Asturias and intend to destroy them and claim their land. I had large supplies of money from borrowing money from the jews and banishing them all from the land and seizing their gold. My only enemy now are the no good backstabbing English because the others are too weak to oppose my three united kingdoms. But then I realized. I had became what I had hated in the beginning. I was a lowly single state and then got power, and became the bully.
Oh and there was alot of incesting/cousin marriage/uncle and son/daughter to breed for amazing heirs and children lol.
tldr: amazing game.