You get a twofer.
If it’s a system, I guess it would be Old School Hack. I don’t think we explored that enough. Mostly because of my own game design fever and forcing my crew to playtest all my stuff.
If it’s a campaign, I’d go with our old Middle Earth campaign. It was truly epic with just crazy plots and subplots, lots of memorable characters, and it was Middle MF Earth!
#RPGaDAY2015 is the brainchild of game designer Dave Chapman. Basically, each day in August there is a question about RPGs.