aramis erak
Legend
For generic?With all this understood, what system do you think is a good generic system for science fiction roleplaying?
It depends upon one's taste in rules mechanics. And, to an extent, setting.
I don't think any one system is universally suitable for all sci-fi if it's rules medium-light (2 of 5) or crunchier. And I don't think Rules Light (1/5) or ultralight (0/5) are of much use for supporting setting tropes — they only work when players (including GM) agree on what the setting is, where the limits are, and to stay in genre; I find that to be a problem, not a benefit, and seldom recommend such.
So, shortlist of ones I'd use now for other than their core setting: Free League's Alien & Coriolis: The Third Horizon, Cepheus Engine/Mongoose Traveller 1e (but never for the OTU - for the OTU, I'll stick to MegaTraveller), FFG/Edge Star Wars.
Generic Engines (& genre engines) I'd consider using: EABA, D6 Space/D6 Adventure, Savage Worlds, Hero System, Advanced Marvel Super Heroes (aka FASERIP Marvel, AMSH), Mekton Zeta, Cortex Prime/Firefly/Marvel Heroic RP.
Some I won't use for sci-fi, but others might find useful: GURPS, Fate Core, Fate Accellerated.
A couple I won't port but others might: Modiphius' John Carter of Mars, Star Trek Adventures, and Dune.
Note that AMSH I've considered using for a battle-armor drop-troop type sci-fi game. It also can do a Guardians of the Galaxy type sci-fi. It's more about adding limits than tweaking existing rules or adding new mechanics. But I've also considered D6 Space, EABA, and Mekton Zeta for same. With the right players, FAE could work, but I lack those at present.
The issues with porting content to Traveller/Cepheus are due to needing to tweak character gen and the tech scale for various settings. Traveller's tech scale is quite dated, even in MGT 2024... and Mongoose has only slightly tweaked it.