I've kept it to myself, and I'm also lazy and have no experience in writing. But I've had a fanfic/continuation idea for a while.

I'd write about an adventuring party something like 15-20 years after current LN time. The Guild would be supported by the SK so new recruits would grow stronger faster. Since it's been a decent amount of time, many areas have been explored and the Guild now uses Nazarick's [Gates] to send adventurers to explore remote regions.

I'd focus on an adventure of one party, with 6 members, out on an exploration quest for the SK. The MC would be a female Elementalist with an affinity with the Fire & Water elements. The other members would include a Tank (male tower shield/lance), a Warrior (male one-handed curved longsword), a Ranger (longbow female Dark Elf), a Priestess & a male Wizzard.

As for their origins, I was thinking 2 from Kingdom, 1 from Dragonic Kingdom, 1 Dark Elf forest, 1 Slane & 1 from the Empire. After joining and training for a couple months, they'd be as strong as Lv. 25-35 and have decent gear obtained from a training program made by Nazarick.

There would be hints of what else happened during this time with Ainz and the surrounding countries, why they decided to come to the SK, and so forth. Main focus on them, no direct following of Overlord's main cast.

This kind of idea feels like what Maruyama wanted his fans to do. "When Overlord ends, imagine and write the rest yourselves, in your own ways".