RetroGaming

Terranigma. Still my favorite RPG to this day and one of my favorite games to this day, but it's hard to gush about this game without any spoilers and its written in a way that requires a bit of attention from the player. You do need to either have an EU / PAL SNES or emulate it though, because it never released in the Americas due to publisher drama.

Secret of Mana is great too, or if you already played that, Seiken Densetsu 3, which is the sequel title that never got released in the West, but got fan translated roms out there. Seiken Densetsu 2 being SoM, and the original Seiken Densetsu 1 was released as Final Fantasy Adventures and sort of a side story to the Final Fantasy franchise, which got dropped and became its own franchise with the second game. SD3 (or "Secret of Mana 2") is a significant step up to the first game in many aspects and even has multiple characters & branching endings based on your character selections.

On the PC definitely the Command & Conquer's Tiberian series, starting with the first game and a GDI campaign run, followed by a NOD campaign run. It got those cheesy but amazingly entertaining little clips between the missions that actually get you immersed into the story and it has a killer soundtrack too. It's one of the many great franchises ruined by EA, but I heard the remastered version is actually decent (I still won't buy because I still boycott them). The already suggested Red Alert is a spin-off series with some references to the Tiberian series, so I would not start with that one until you played the Tiberian one.