The Vanishing of Ethan Carter uses Unreal Engine 3 as a game engine.
http://en.wikipedia.org/wiki/Game_enginehttp://en.wikipedia.org/wiki/Unreal_engine_3#Unreal_Engine_3http://en.wikipedia.org/wiki/Unreal_engine_3#Unreal_Development_KitIt's possible for a game that uses Unreal Engine 3 to allow you to save anywhere --
For example, the Fable Anniversary Wiki at
http://fable.wikia.com/wiki/Fable_Anniversary lists the ability to "Save anytime, anywhere, including during quests."
But as far as I can tell, the ability to save anywhere is not the default
for the Unreal Development Kit, and requires extra work.
Here's a website that describes how to incorporate saving into a game.
http://udn.epicgames.com/Three/ConfigSavegameSystem.htmlI have no idea how difficult it is for a developer to incorporate saving
with Unreal Engine 3, but it looks non-trivial to me.
It's possible that the developer tried to incorporate saving but the result was unstable, producing bad saves or crashes.
Or the developer may have had some idea about how they wanted people to play the game which did not involve saving anywhere. Or maybe they just didn't think saving anywhere was that important for this type of game, considering how much extra work it would be.
Adding a save anywhere feature to a game after the fact is difficult if not impossible.
You usually end up with something resembling "checkpoints" instead of "save anywhere" saves.