Mine is playing AOE2 in easiest (or standard if I want a bit of challenge) mode against 3 bots. I just build my economy, wall up (and laugh at the enemy soldiers attacking my walls in vain), reach imperial age and attack once my army reaches the population limit. I also send 104 in the chat so they don’t surrender and I can enjoy razing their all buildings one by one. If any of them builds a castle, even more fun. A build a trebuchet and watch it raze the castle from a safe distance. If there is sea, after I am done with the land, I build 3 docks, do research and build a navy and hunt down ships around the unxplored sea. It is fun, satisfying and relaxing.
What is yours?
Doing dumb runs in EU4 while cheating. I give myself a few techs at the beginning of the game to be stronger than everyone else and focus on my objective.
For example, Hindu Hungary, Jewish Arabia, Totemist England, Tengri Russia, Protestant Ottoman Empire, destroying France as a small East Asian country and forming it again by culture converting, being Emperor of the Holy Roman Empire by starting with an African country etc.