Will Not Let Me Go

This isn't really a game, but a short story (or medium-length story, I think it might have taken me 2 hours to play through) that is very engaging and makes clever use of the mechanics of Twine to make you feel what the main character is feeling (like when (Spoiler - click to show)you click on a word to choose your path and the word changes in the updated text). The ending was both great and heart-breaking.

ADDENDUM: The more I get into IF and also away from the idea that all IF should have "gameplay" elements the more I appreciate this piece. It is primarily a linear story, but one that makes use of the interactive aspects of IF very well. Will be on my Top 50 ballot for a long time.