Steam tells me that I have 381 hours in the first Spelunky, but a mere 74 in Spelunky 2. The reason for this is simple: I'm terrible at it to such a spectacular degree that my clumsy attempts in Spelunky 1 look like virtuoso performances by comparison. But perhaps I'd get more into the second game if it were transformed into a Metroidvania.
Thanks to Spelunky: Wrath of Kali, I can find out. Spotted by GamesRadar, Wrath of Kali is a sprawling mod for Spelunky 2 that converts its constantly shifting world into a fully-authored Metroidvania. Created by a "small dedicated team of modders in the Spelunky community," it's currently only available in demo form, with a release planned for later this year, but even that demo looks impressive.