I like the idea. It's sad to hear that you ran out of time to put in the game mechanics: as of now, we don't have all that much ability to prevent our charges from being grabbed by the endless void. That's fine if that's what you're going for, inevitability is common enough as a game theme especially with the reaper.
Music, the footsteps, and the clinking chains are very substantial for the game's ambiance. The moral choice at the end would have more weight if there were more of them: 3-4 days telling the narrative journey of this here reaper would tell a better story, kind of like a visual novel
It's decent. I enjoyed it.