Free HârnWorld D20 Adaptation Approved by the Copyright Holders

Over on DriveThruRPG there is no available HârnWorld D20. From WarFlail's Armoury:

HârnWorld D20 is a detailed adaptation of the gritty, low fantasy medieval setting of HârnWorld, using the d20 System. This is an unofficial product, approved by the copyright holders.

Recommended resources: HârnWorld and HârnMaster, available here on DriveThruRPG.

HârnWorld is a detailed, realistic, flexible, and system-neutral setting for fantasy role-playing games. Since 1983, HârnWorld has been used by thousands of people across the world to run a wide array of medieval fantasy adventures. HârnWorld can accommodate whatever style of campaign you are looking for, whether your player characters are knights, mages, barbarians, clerics, noble lords, mercenaries, gladiators, craftsmen, merchants, thieves, or even simple peasants yearning for adventure.

The best part is that this resource is a free download. While d20 is of course 3.5E converting from that to OD&D on the fly is a snap.

Also on DriveThruRPG are these two HârnWorld products as pay what you want items.

5E Hârn

Want to play in the HârnWorld setting using D&D 5e rules? Here you will find a 'light-touch' adaptation to capture the gritty, low fantasy medieval feel of Harn, while retaining 5e's elegant game mechanics. This is an unofficial product, approved by the copyright holders.

 Again converting on the fly from 5E to the faster, simple, easy to use OD&D system is a snap.

I also enjoy the 'claim' that these copyright holder approved adaptations are 'unofficial', IMO if the IP holder approved it, you cannot get any more official than that. I realize that WarFlail's Armoury is obligated to put out that little disclaimer, but the disclaimer is obviously not true. If it were not official it would not be available.

5E Hârn Bestiary

A compendium of monsters and NPCs that can be encountered in Hârn. It is a GM's supplement for the 5e Hârn rules. This is an unofficial product, approved by the copyright holders.

Note: placing the word approved in bold is added by me.

The two recommended resources: HârnWorld and HârnMaster, are available on DriveThruRPG by Columbia Games along with other Hârn items. 

https://www.drivethrurpg.com/browse/pub/2182/Columbia-Games-Inc

These products by Columbia Games are in pdf format  and while many items are very reasonably priced (and I recommend getting them), sadly some of the most useful items are way overpriced unless you were receiving brand new 1st edition hardback books. It is hoped that someday these items will be priced to sell thousands of pdf copies instead of 10's of copies. Sad really since Hârn is such a beautifully done setting that they would deliberately limit their customer base to a tiny fraction of what it could have been and still could be. ($49.99 for a pdf of a book published in 2002.)