Septerra Core is....a difficult game to recommend. I should preface this review by saying that it is MOST CERTAINLY not for everyone. Septerra Core is an older turn-based RPG from a time where these sorts of games were common on consoles but rather rare on PC. I played the game to completion back in that era, and found it rather enjoyable - however, even then it had its rough edges, and for modern sensibilities it will be rather archaic.
The combat engine is location-based, similar to how Chrono Trigger is. However, the speed/pace everything works at is exclusively suited to when you have 3 members in your party, so combat is QUITE clunky in the early portion of the game, which makes it a bit of a hurdle to overcome.
The cast is varied, and the story was decent for the time (from what I recall - details are fuzzy). The concept of the WORLD itself is rather imaginative, and wholly unique from what I've run into in gaming. Aside from that, level design as the game progresses becomes....extremely maze-like. Lots of wrapping corridors which look same-y and form literal mazes.
Effectively, I'm recommending this because I enjoyed this game when I played it. But anyone who purchases it should know what they're getting when they're going in - a game that was a little rough around the edges when it came out, and which probably won't appeal to most modern gamers. Only purchase if you really enjoy turn-based RPGs, or are interested in very imaginative sci-fi worlds.