I haven't picked out a game or even my schedule yet. In the past I've done
8AM Friday-8AM Saturday
12PM Friday-12PM Saturday
8AM-8PM Friday, 2PM-12PM Saturday, and then 8AM-4PM Sunday

For game, Minecraft is the obvious and easy choice, but beyond exploration and maybe farm building, I don't really have a good idea of what to do... I did get an idea for a way overly-ambitious build, but it would require massive amounts of sandstone and terracotta, so the day would be all resource gathering.

Don't think I'm up to it this year, myself. If you end up doing something convenient for me to jump in on, though, I might see if I can swing it. I still haven't taken my floating holiday for the year.

(FFXI sadly doesn't seem like it gets much attention for stuff like this, though I honestly did have one person following me for a while on my extended "do all the missions" effort. Sadly, I got to a place where I couldn't continue for a long while.)