The VOIDRUNNER'S CODEX is coming! Explore new worlds, fight oppressive empires, fend off fearsome aliens, and wield deadly psionics with this comprehensive boxed set expansion for 5E and A5E!
Technically, not intentionally. I see the book (usually a system) and say "Hey, that looks like fun." I buy the book. I know my group will never play anything other than D&D, and I'll never actually play the game I just bought. But that doesn't mean I don't WANT to.
All the time. Though I'm looking forward to start my first Ghostwalk campaign, almost two years after I purchased the book. I'd like to play Castle Falkenstein too; I own the book and love it, but never got a chance to play.
Never. Ever.
All my gaming purchases affect my way of running a game and its contents, one way or another. Some aren't directly played or used, but they always influence my games somehow, by giving ideas or striking me as "something I really would not enjoy".
All the time, although I rationalize by telling myself, "Hmm... I might want to use this for reference sometime!" About 20 or 30 GURPS sourcebooks alone made their way into my collection like that.