i think the one really unique attribute that had a deep impact on the series was the romance development in the storyline. hell its on the cover of the game title with squall holding rinoa. up until this game there was never as well drawn out romance story development in the final fantasy series. cecil and rosa were together at the beginning of ff4 so that doesn't count. If there is any romantic relationships that developed during the storyline in previous final fantasy games between some of the main characters its usually vague and mainly left for the players imagination like aeris and cloud or celes and locke. not really covered in detail just hints to a possible romantic relationship between the characters. and the inner thought dialogue of squall was really different as well at that time, but didn't have a strong impact and wasn't picked up by any of the more recent games in the series. Cloud had his crazy breakdown inner dialogue thoughts as well but they made squall's thoughts a major part of the storyline. In my opinion that can really help character development in the storyline. the song eyes on me had a huge impact as well. Eyes on me was probably one of most memorable things of ff8. Think that's why ff9 had melodies of life song in it. but as far as battle system ff8 was the first to raise lvl cap to 100 (i don't think any later final fantasy game copied that idea tho) It was also the first to have over the cap damage feature in it with kamikaze and eden that could hit well over 9999 traditional cap in one hit. ffx, and ffxiii went much further with that idea breaking outside the traditional cap. As for junction system I think it was different and unique but did not have a strong impact on the series. I like ff8 a lot but junction was an epic fail and its biggest downfall imo, and im pretty sure squaresoft realized it too, because they seemed to make a point in ff9 to go back to a more traditional armor and spell system.