I keep a spreadsheet with details of all games, who I bought them from, for how much, etc... I occasionally update as market dictates. I also have contact info and trusted friends contact info so they can assist with stuff and written out what games they will each get in exchange.
There are a few people specifically listed as Do not sell (I have rare games that a few may want and F them. They were dicks when I was alive so they can suck an egg when I am gone, lol) and my friends will honor that.
If/when I die then these details should help whomever has to deal with material shit.
I don’t plan a big sell off at any point when alive but I am still relatively young and healthy so that could change I suppose.