That's a tough one. I do a lot of my gaming on console, also, these days so that kind of muddies how I would answer a bit. Also depends on when you catch me. But for right now, it would definintely be Banished, Cities Skylines, Civ 6, Fallout 4, and Arma 3.
If I could spread it out across PC and console it would probably look more like Banished, Cities Skylines, Borderlands 2, Borderlands: The Pre-Sequel, and Fallout 4.
Tough one though...Depends on how long I was going to be stuck on that island. lol The EQ obsession pops up again every few years so might have to bump The Pre-Sequel for EverQuest or one of the EMUs. Assuming there was internet access.
Fun stuff.
Your post reminds me I'm due for some Heroes of Might and Magic. Haven't played one since 2 or 3 ages ago.
EDIT: I put Civ 6 on there because I haven't played a Civ in ages and it's on the top of the list to check out before too long. But so is Transport Fever. So there's that, too. Much easier question if it were 10 rather than 5!