Core mechanic for new TTRPG
I'm developing a TTRPG adaptation of a popular video game franchise and, in the interest of keeping true to the source material, I want to break out of the d20 mold. Problem is, that's the only system I've played; even pre-2000, I only ever played TSR's AD&D and ALTERNITY, which are fundamentally precursors to the turn-of-the-millennium d20 system and its WotC successors.
So, what are some core mechanics others have enjoyed over the years? What made those mechanics enjoyable? I'm leaning toward essentially replacing the d20 with 3d6 to reduce the impact of luck on task resolution, which I think is fine, but I don't want to leave it at 'fine' when 'great' might be a reddit post away.