Bonus points for any non-D&D or D&D derivative systems.
My first RPG was Palladium Fantasy way back when my grognard uncle invited me to his groups table. I still don’t really grok it, but it was pretty formative of my ideas of what an RPG could be. The lack of balance and extreme existential threats as part of ordinary encounters included.
Needless to say, I haven’t found a group for this system in a looong while, eheh.
For years, all our group played was Palladium (Rifts, FRPG, and Heroes Unlimited), but I don’t think I’d ever go back to the system given other options. Combat took forever (possibly bc the GM’s threw ungodly amounts of enemies at us and refused to have anyone retreat, ever) and it felt like it just generally took forever to do anything. Also, there’s not really many adventure modules in any of the books (apart from Sourcebook 1? Just random ideas for things, but nothing to tie it together). We’ve since gone to a few other systems, but I still like to run one-shots and try out new systems whenever I can. I’ve had Year Zero in my sights for awhile and I’m prepping to run Mutant Year Zero, hoping it goes well.
Rifts was my first TTRPG and it opened up the whole RPG world to me. Absolutely loved the blend of magic and sci-fi.
Combat system was clunky as hell though.