EDIT: I've started working on this
Play Alpha 3: http://bitrim.org
Think Myst/Amnesia(without free-roam)/Escape the room, but in full 3D, and with a much higher concept story/setting. That means not some weird Myst world or a generic Cthulhu horror.
Let's say they were episodic-style, and maybe £2.99-4.49 ($4.80-7.30) each.