Wikipedia claims that Brian Stowell's Dunveryssyn yn Tooder-Folley (The Vampire Murders), published in 2006, was "the first full-length Manx novel". This claim is sourced to a 2006 new article from the Isle of Man Today, which is archived on the Wayback Machine and claims that Dunveryssyn yn Tooder-Folley "is believed to be the first full-length novel written in Manx". These weasel words aren't enough to satisfy me. Given that Manx literature has a centuries-long history, it might be surprising that the first Manx novel would be published in 2006, but then again it probably depends on what's meant by "novel".
Is it true that Dunveryssyn yn Tooder-Folley was the first novel that was originally written in Manx Gaelic?
I realise that the answer may depend on how we define "novel", but let's be clear at least that translations from other languages, including other Gaelic languages, don't count. Are there any other contenders from Manx literature that might be considered to be "novels", from earlier than 2006?