Final Fantasy X HD

[Kain Nobel]

The sphere system was interesting because, while it gave every character a linear path to learn new skills and stat augments, you could deviate to other places on the board by using the Lvl keys. I haven't played it in probably about a decade, but I think when I beat it last I had pretty much 90% of the board learned for every character.

As far as sequels and spin-offs, Final Fantasy X-2 was probably my favorite. I suppose the plot on that one was kind of dumb, but the battles were really fun because you could change your "class" on the fly with dress spheres. The only thing that could've made that game better was if they had a hidden Naked dress sphere ;D