Some minor spoilers for Ringworld and Known Space. Beware if you haven’t read the books and you care about minor spoilers!
I dunno…I love Niven’s Known Space, but there’s so much background to it by the time you get to Ringworld that I’m not sure how you’re gonna explain it all.
Off the top of my head:
A) Boosterspice/the Body Banks/the Birthright Lottery which are needed to understand the whole “Teela” Gene thing. (Remember: in the first book it wasn’t a fraud)
B) The Man-Kzin Wars/Outsiders/Hyperdrive (if it isn’t dealt with in some detail, Nessus’s big revelation about Speaker’s being a “tame” Kzin becomes meaningless)
C) Pak Protectors/Tree of Life (try to explain that in few sentences!)
D) The Slaver-Tnuctipun War/Stasis Boxes (remember the Sunflowers?) And Ringworld, in book one was thought to be a Slaver artifact, right (or was it a Pak artifact?)
There are more integral items (the Core explosion/General Products Hulls/the Puppeteer exodus) to the story, but you get my point.
Sure, you could throw these items out, but they’re what make Ringworld interesting. It’s not the fairly flat characters (Speaker’s the only one who’s fully developed. Best line, paraphrased “The meat is not fresh” said Speaker, dubiously watching Louis grill a steak with his laser “but I’m not certain that cremation is the answer.”), it’s not the plot, which is a “Wizard of Oz” type story (spend most of the book travelling somewhere to get home only to find your method of getting home was right where you started), it’s the ideas that make it a classic.
Niven, in his prime was the most explosively imaginiative SF writer ever, IMHO, tossing out more ideas in a single short-story than other writers might toss out in their entire careers. I’d love to see some of his stuff adapted: World of Ptavvs (with a different title) would be great. A Gift From Earth? Maybe. Some of the Beowolf Schaffer stories? Wonderful! But Ringworld? I dunno.
Fenris (who thinks if anyone could pull this off, James Cameron might)