Dogfish Head first brewed World Wide Stout in the '90's to set the ABV record for beer, which it did, although it has since been broken. Usually clocks in between 15 and less than 20. I think my most recent bottles are labelled 18.
About 20% ABV is when the yeast die happy instead of fermenting more which means exceeding 20% requires special techniques. Last I checked the ABV record for beer was about 67% ABV. It was brewed at near freezing temperatures where the yeast could survive a little before the alcohol killed it. Seems to brewing was a several month process involving a lot of freezing and maybe even several strains of yeast.
120 Minute IPA and World Wide Stout have a lot of similarities considering lower ABV stouts and IPAs barely have any. Much of the flavor comes from the high alcohol and not the mash bill.
I will drink either when I find it on tap and go for WWW when both are available (which happens a couple of times a year).
Price in this market is a 4 pack of 12 ounce bottles for $45 minus some change.
I friend and I once made a Black and Tan by mixing a bottle of 120 and a bottle of WWW. it was very, very good but neither of us thought the mix was better than either beer alone.
If you are interested in taste and not the buzz most beers over 11% really taste different and the Double or Imperial version is not necessary the best tasting. But I'll drink all the WWW I can afford.