The third part in the PS1 trilogy, I loved this game. I'm a sucker for Armored Core Arena games, and this one does not disappoint. There's even a function to carry over ACS from previous games and make a custom arena, which I actually wish I had more time to mess around in.
The storyline is pretty interesting, and works well off of the other two games. There are more parts, and multiple arenas to test out your creations. This one is just so much fun.
This is definitely one of my favorite series in the PS1 era. That in, buying a physical copy of this is insanely expensive. The current PS5 version Is unfortunately missing the functionality to carry over your AC from the original armored core game to this one (as of this typing). Which is a definite shame. If these games came up on GOG, with that functionality intact, I'd buy them in a heartbeat.