I just sit there and wonder what I do next for the rest of my life lol. In all seriousness I always get the void after finishing a really good game, I think it is just because our expectations are so high for the next one. I normally start a few games that are in my library and play a few minutes to see what i am in the mood for. Sometimes just seeing something random or talking about something steers me in the right direction.
For example, I was looking for something to play a few weeks ago, I always replay alittle of FF7 every year so I started that. I went from there to Dragon quest 8 which a played alittle bit of and ending up on playing Tales of Berseria which I am sinking all my time into