Time to call Guinness and challenge for their next publication.
Actually, I think the Guinness World Record team got it correct, and it is Larry who, after all, is a bit confused with facts
Following Larry's logic, UnReal World development time was about 18 monts - Sami started developing some time at 1990, and the first playable version was released around may 1992. The first version was released as share-ware, and according to the standards of those times, it counts as 'a public release'.
Since 1992 UnReal World has been receiving a continuous stream of updates - which is different from the 'development hell' Larry describes with those other games. Also, thas is why UnReal World can't hold a Guinnes World Record for longest development time.
Instead, UnReal World has the official Guinnes World Record for
longest update support.
So, no need to call Guinness to challenge their nominations.