Digital distributor GOG kicked off its Christmas sale today with a cracking Bullfrog bundle and the very kind offer of Duke Nukem 3D for free. I do apologise for the following awful joke but, this being a video games website, I'm contractually obliged to crack it: as Duke himself might say, "Come get some!"
Yes, Duke Nukem 3D: Atomic Edition, which includes the expansion, is quite free.
Costing a bit more, but only just, is 75% off a fine bundle of Bullfrog games including Syndicate, Dungeon Keeper, Magic Carpet, and Theme Hospital. You get 8 classics for only $11.92, or can buy them individually at 50% off. It's the first of many daily deals.
GOG has plenty more on sale, so hit the site and delve deep.