One of the Paradox strategy games by a comfortable margin. It'll be one of the Crusader Kings or Victoria games. I've got a weekly game night with a couple of friends that was originally just CK, but has for a while now been working extremely slowly through a megacampaign. You can take the end of Crusader Kings and make it into a mod for the start of Europa Universalis, then repeat the process into Victoria and then Hearts of Iron. You need to set some rules for yourselves, because an experienced player doesn't need even a third of the CK timeline to demolish all AI threats, but the games are already good roleplaying fodder anyway so you can set rules that play into that. We're currently about three quarters of the way through Victoria

Outside of those, Noita or Deep Rock Galactic. For a while, those plus a podcast were my go-to "zone out brain off" relaxation, so the hours racked up