Recently, due to legal shenanigans between Bethesda and Interplay, Fallout 1,2 & Tactics were taken off the virtual shelves of pretty much all digital distribution stores. However, Bethesda announced on Twitter that they are currently working to bring it back to Steam.

Unfortunately for those of you who prefer not to use steam, when asked about returning to GOG, they responded "Our priority right now is returning the games to Steam at the earliest date possible" so coming back to GOG is on the backburner for now and might not happen for a while. Thankfully, pretty much everyone who uses GOG or has even heard of GOG got all of them for free and can still download them.