I've replaced most of my physical collection of #GURPS 3E books with their ebook counterparts - nostalgia or no, they just took up too much shelf space.
The main exceptions were licensed books, since the licenses have long since expired and Steve Jackson Games can no longer sell them. And GURPS War Against the Cthorr holds a special place in my heart among these books, since the notion of an alien biological invasion was utterly fascinating when I read it - and it still is. After all, while you can "hunt bugs" with the usual array of weapons available to typical adventurers, what do you do when a hostile ecosystem transforms your world into theirs? How do you fight that? #ttrpg