Today is the last day for this, and they haven't run out of keys! DOOM! $10! BETTER THAN SWITCH VERSION!
Also, in my OP when I said "original 3" I mean Doom 3. It comes with the original games and official expansions for Doom and Doom 2. It's just that Doom 3 is BFG Edition (which also includes Doom and Doom 2 WITH ACHIEVEMENTS), not the original version.
There are minor differences. The gameplay related ones I think can be toggled so don't really count? The rest is the engine updates to modern hardware support, creates more lighting sources, less compressed audio, support for 3D displays, etc. If you haven't ever played it, you wouldn't know except that I'm telling you and you can probably find hour long rants on YouTube about it. I think there's mods to change most stuff back if they aren't options in the game.