Brett, you inspired me to poke through my collection for what I'd consider "forgotten."
I have Hahlmabrea, Ravenstar, Periphery, Spacetime, and Journeyman that I'd suggest for future posts on the blog. Brief summaries:
Hahlmabrea: By Daniel A. Fox (not Daniel D. Fox of Zweihander) is a pretty generic fantasy game published by Sutton Hoo Games in 1991. Percentile skills. No classes. Different spell lists for Mages, Sorcerers, Wizards, and Witches. Playable Centaurs and Two-Headed Ettins. The Dread Pigasus. I've never touched it, not even to mine ideas from. Just doesn't click with me.
Ravenstar: By A. Siddiqui is a space-based cyberpunk type game by Raven Star Game Design in 1994. (I think I picked my copy up at GenCon '94). Uses a d20 for skills, but d6s for damage. Thinly veiled fantasy races as aliens, including Bear People. Lots of cybernetics. Lots of gear. This game appealed a lot to 18-year old me, and reminded me of CP2020 at the time. I haven't opened it in a while, but the production quality for 1994 small press seems pretty good. The art is a serious mashup of some pretty decent pieces and some of those mid-90's "I want to be a comic book artist when I grow up and learn to draw hands" characters, as well as some early "futuristic" 3d digital pieces. I don't regret having it.
Periphery: science fiction roleplaying on the edge. (sic) by Gareth-Michael Skarka and published in 1993 by Epitaph Studios. This was apparently (based on the dedication) his first work. "Gritty" sci fi that seems to include wizards and people in lots of cloaks. Percentile skills, but calculated from 1-10 stats and low skill number ratings multiplied by difficulty to determine the skill rating for that task. Wound-based damage system in combat. The art...across 3 pages you get early computer line-art (think MS Paint), a photo of an unpainted mini, and a scan of someone's hand-drawn art that looks like something out of early HoL or Battlelords. Lots of tables. Not much use, tbh.
Spacetime: 1988 by Greg Porter/BTRC. Greg Porter's Guns! Guns! Guns! gets a lot of love in the hard-numbers crowd, but this is the only version of the TimeLords rules I've ever seen in the wild. A time-travelling sci-fi game with BTRC's classic unified weapons and technology theories. Stats are 1-20. Skills the same range. There's a table for calculating modifiers, and you use a d20 for success rolls, but everything translates to nice percentages and he says "Use those if you like." Point-based character design, single interior artist (Thomas Darrell Midgette) that leads to a nice, clean and unified late-80's line-art scheme that's always appealed to me. BTRC's stuff is phenomenal to the people who like that sort of thing (engineers and mathematicians... think about Traveller Fire, Fusion, and Steel. If you're not having a PTSD-like reaction, you'll like this).
Journeyman: 1989 by Frederick Goff, Infinity Games. A Traveller/Space Opera clone Sci-Fi Heartbreaker with a different skill system. Much more succinct than either of the inspirations, but it has some wonky effects like die-based skill levels (as in "roll for your starting level in the skill") and hit-point based damage with a d10+skill task system. Quite a bit of effort went into his planet and alien generation systems, though, and I've had occasion to pull the results of those for translation to Traveller before. The art is.. small press. It's the same two guys throughout, and their styles are very similar, but there's aspect ratio issues and a general graininess that puts me off it. The real gem is in the back of the book, where there's simplified formulas for just about everything sci-fi related. Need to know the orbital period of a given planet? Right there (T= sqrt(15,750(R+(d/2)^3/d^2g)/3600 ...isn't that simple!) Equation to determine payments when financing? Also there! Theory on the Nature of Hyperspace, complete with Einstein and the author's own formulas? Boom. (essentially, his theory is "Take the complement of our universe" which means 1/x for all rules and formulas. I won't scare the normies with more math though...) So I both love and hate the book.
Anyway, my quick recommendations if you're wandering through your stacks thinking about what to pick next, Brett.