Mim is the Gollum of the First Age, and I wonder how much of the character Tolkien recycled when writing the Third Age books. Compare lines like "I am old and poor. Only a Dwarf, as you say, not an Orc, Mim is my name. Do not let them slay me, master, for no cause, as Orcs would" to any of Gollum's pleadings in The Two Towers.
* * *
Beleg's gift of lembas, at the end of the chapter, is interesting. Lembas-bread was created during the writing of the Lord of the Rings, so its presence here indicates that this was one of the sections rewritten by JRRT after the Lord of the Rings was published. Given that lembas is... analogous to the Host, Beleg's line "Eat it not, if it sticks in your throat" isn't just a response to Turin's statement that he will not "receive gifts out of Doriath", it's also a moral test, which Turin passes.
"Turin's eyes glinted, but as he looked in Beleg's face the fire in them died, and they went grey, and he said in a voice hardly to be heard. "I wonder, friend, that you did not deign to come back to such a churl. From you I will take whatever you give me, even rebuke. Henceforward you shall counsel me in all ways, save the road to Doriath only".
* * *
Thoughts on a First Age rpg campaign: start it with the arrival of the Sons of Feanor from Valinor. Each PC is an elf-lord with their own following. The campaign takes place over centuries - building your hidden kingdom to defend against Morgoth's hordes, and making alliances and rivalries with other players is vital. The action is epic - one PC can take on whole armies - but when a PC dies, the player then switches sides to evil and becomes a named minion of Morgoth, adding to the ever-growing power of badness.