well, there's that mod. but there's also the press-release wording in the general section, distinct from the scenario section, that says:
"Expanded Epic Game: We've added more new units, buildings, and technologies to the epic game with a tremendous amount of effort focused on the late game." (that's a direct quote)
i've seen the devs answer questions about it, because it is strange phrasing. they say that in that context, they mean "epic game" to refer to "BtS straight-up, unmodded and not in a scenario, regardless of game speed". (that's my paraphrase)