Tim Cain from Obsidian Entertainment talked about RPGs this year at Croatia's Reboot Develop. It was a pretty great talk. And you're lucky! They recorded it. xD
There are some really good points for everybody who wants to develop RPGs. One of the points that really resonated with me was avoiding numbers which seems counterintuitive since numbers are kind of a core thing in RPGs. But the thing is: they are not. I haven't watched the video so I hope you can see the slides properly since there are some important visual things that he shows.
BTW, the actual talk is less than an hour even though the video is 2 hours long.
EDIT: Quickly glanced through the video and yes, the slides are properly visible. Have fun!