Not Runescape but a similar grindfest - playing the largest Factorio mod, Space Exploration. 300 hours plus in ~5 hours of video

https://www.youtube.com/watch?v=8hRJ-CcwvrI&list=PLtyo3aqsNv...

There are definitely factorio mod(pack)s which are more of a timesink: seablock and pyanodon's spring to mind.

Start with Settled's swampletics.

https://youtube.com/playlist?list=PLWiMc19-qaA3u1ZawZQIKAh0B...

The other good one from the same channel is Tileman, where he is limited to only using tiles that have been "unlocked"

His current feature is Lowlife, where if he takes a single point of damage his account gets deleted.

Two "extreme one chunk" style accounts in which the creators are or should be heavily medicated.

Verf - https://www.youtube.com/@VerfRS

Limpwurt - https://www.youtube.com/@Limpwurt

Not op but one my favorites is: https://www.youtube.com/@Settledrs

Very entertaining to watch and explains things so even non players can understand the sheer absurdity of some of the attempts.