I thought about a tribute and the Keen 1-3 Patchwork Mods put together by Levellord (and later also Levellass) came to my mind. I contributed to two of them and it was a cool experience.

They were released between 2004 and 2008. A lot of things have happened since then, many more Keeners got into Galaxy modding. So why not take the challenge of creating a Keen 4 Patchwork Mod, more than 10 years after the third one?
Before any levels are made, the various sprites should be collected at first, I think. There are about 20 actors in Keen 4. When Levellord curated Patchwork Mod II, there was a list of the sprites and one could see which graphics are done or in the works, so that multiple people won't work on the same one, if I remember correctly.
When the actors are finished, anyone who wants to make levels would receive the latest state of the mod and be able to work with the actual creature replacements, including those with changed size and behaviour. Thanks to the vast number of tiles available in Keen 4, each participant could also give their level(s) a unique appearance this time. And the musical ones could contribute their songs, too.
Regarding the plot and theme, what about something like this: The planet "PCKF II" is inhabited by the Keeners, fans of the Defender of the Universe. They are preparing the celebrations for the 20th anniversary of the day they made "PCKF I" their new home. Party decorations are all over the place. However, the not-so-fun-loving Shikadi kidnap the eight immortal "Guardians of Keenishness" and scatter them across the planet. The Guardians preserve the stability of PCKF II, a world that exists thanks to the power of creativity. Suddenly, the creations of the Keeners turn against their creators and everything is thrown into chaos. The mastermind behind the evil deed is Mortimer, of course, with the intention of destroying the community made up of his archenemy's biggest fans.

But a coherent plot would not be the focus of a Patchwork Mod, it's all about the fun with pixel art, level editing and composing.
What do you think? I'm sure the result would be amazing, no matter whether it gets finished until April 2020 or whatever occasion is used. Maybe you think the theme is stupid and it should be something entirely different. Well, all what I wrote are just suggestions. But anyway, the last Patchwork Mod came out more than a decade ago and I always wished for a sequel.
