Jenny, that's interesting! It seems as though the extras offered - poster, soundtrack, etc. - only pertain to Black Mirror 2 however. Maybe the file is just larger because they are offering different language selections? It's only speculation on my part; I haven't downloaded the game yet since I already have the disk version installed on my computer. Maybe my curiosity will get the better of me, and I'll try it out sooner than expected just to see what the reason is.
If the download does included Black Mirror 3, then we really
got a bargain with two games for little over 2 dollars.