Soon to be released, That’s a Goblin!?, Spes Magna’s first OSR game supplement. Written as compatible with Swords & Wizardry but usable with other OSR fantasy RPGs, That’s a Goblin!? introduces ways to make your game’s goblins different.
The free preview PDF at this link presents 23 random goblin mutations. The final version of the PDF in the works includes not only the goblin mutations but also goblin types, tactics, weapons, and stat blocks for sample goblins.