Also not listed in the first post, "The Dragon's Eye", which Jonathan Tweet has reportedly finished the manuscript for:
https://www.chaosium.com/blogchaosium-announces-runequest-the-dragons-eye-is-in-development/
Seem to be quite a few things missing from the RQ Classics section?
https://www.chaosium.com/trollpak-pdf/
https://www.chaosium.com/runequest-companion-pdf/
https://www.chaosium.com/soloquest-classic-collection-pdf/
https://www.chaosium.com/pavis-pdf/
https://www.chaosium.com/gateway-bestiary-pdf/
https://www.chaosium.com/big-rubble-pdf/
Plus Wyrms Footnotes 1-14:
https://www.chaosium.com/wyrms-footnotes/