Dear Esther was quite a hit amongst the mod community; next month developer thechineseroom will be releasing a fully legit version of it on Steam. To celebrate and promote the impending launch, a trailer is below. It's very well-presented and intriguing, though you may find yourself waiting for the 'game' part to kick in (it doesn't).
Dear Esther places you on a deserted island, where you find yourself driven on by a voice reading a letter. It launches February 14.