All We Love We Leave Behind

From the introduction:

All We Love We Leave Behind (AWLWLB) is a single-player RPG examining longing, loss, and love. In this game, you will play the Writer, a character who stays home when the Absent, someone they love (a parent, spouse, sibling, friend, etc,) must leave. You will write letters in character as the Writer to the Absent, but you will not receive any in return. AWLWLB is meant to explore feelings of uncertainty, absence, and isolation, your letters hopefully will reflect that. When you’ve finished playing, you will be able to go back and read the letters in chronological order and watch your character’s evolution, whether that be for good or ill.