Three quick points:
1. As a reminder, Open Fridays are a replacement for my daily posts on Friday when I'm offline. I write them in advance and don't participate in the comments because I don't see the comments until the next days, by which point they're usually too many in number for me to even hope to keep up, assuming I ever intended to do so (which I didn't).
2. That said, my own personal candidate for an underappreciated pre-1984 RPG is probably Stormbringer. Lots of people know about the game's existence -- note I said underappreciated -- but, in my experience, its virtues are not well-known. It was overshadowed by its "big brother," RuneQuest and many gamers dismiss it as a licensed game, either because licensed games are often poor or because they had little interest in the world of Elric. Neither is true in the case of Stormbringer, which both shows the flexibility of the Young Kingdoms as a setting and has really evocative rules for dark fantasy even if you choose to play the game "generically."
(I'll also agree with several others that both Lords of Creation and Powers & Perils deserve nods as underappreciated RPGs, which, like Stormbringer, often get dismissed for false reasons)
3. On the subject of energy drain, I'm still very divided. I like many of the suggestions offered by people in the comments, some of which look elegant mechanically and intriguing from an in-game perspective. However, despite my misgivings, I've yet to decide to abandon the existing mechanic, which, as other people have shown, work from both perspective, or can anyway, with some work. So, for now, energy drain stays in Dwimmermount as written.