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?
You might also enjoy hiking, which is pretty much those two things but mostly the first.