Anyone get the suspicion that the Oort might be the D’ni by a different name? 
Mysteriously dead or gone civilization
Remnants of their civilization are strewn about many, many worlds.
Said worlds are connected via portals
Many of those worlds are very …unique, and possibly obey different laws
They use an interesting runic (and probably highly structured) numeric system
They’re viewed as largely benevolent
Did the Oort, perhaps, make all these worlds we’re playing on?
No 
that’s silly
hehehehe, nice idea, but the portals are not in books written by creators and I also (til now) didn’t need a walkthrough to find where those goddamn thingies are hidden and how to take on the riddles that block my way from them ;D (ever played Riven? … That Part was quite nasty in terms of riddle compexity ^^)
Half tempted to build a giant book around one of the portals…
(spell my nickname backwards, heh. Original, I know :-/)
For me they were as selfish a race as we humans are^^ Which would explain why they are gone even though they were so advanced.
or maybe they were just too curious for their own good.
(hey, what happens if I put this ultimate power crystal into this singularity drive and use it to divide by zero?)