Every Earthbound fan knows the long road its sequel took. Watching as development was moved from the SNES to the N64, then to the N64 Disk Drive, then back to the N64 once that thing ended up becoming a massive commercial failure, then cancelled completely after countless delays because of the development team's lack of familiarity with 3D design and the advent of the Gamecube rendering the N64 irrelevant. After several years, the game's development was revived on the Game Boy Advance as a 2D title before finally being released in 2006. So all in all it took around twelve years for a proper Earthbound sequel to finally come out... only to be denied a Western release by Nintendo, who were all along unimpressed with mediocre sales and middling reviews of its SNES predecessor in spite of the cult following it had acquired.
Thankfully, a dedicated team of fans were on the case and created not only a complete translation of the ROM, but even a full player's guide in the style of the one packaged with Earthbound. So while we may never see a proper release of the game in English, we can come pretty damn close with this at least.
As you may expect from such a long and difficult development, Mother 3 has some significant differences from its predecessors, not the least of which are some interesting new features. Character animations are significantly more intricate this time, with new frames for things like special plot scenes, running and even proper speaking animations during story scenes so you can tell for certain who's saying things. Combat is still in the same turn-based style with text narration in lieu of full animation, but there is a new mechanic in the form of a small rhythm game for normal attacks - by pressing buttons in time with the background music, you can land additional hits with music notes and cause slightly more damage.
The game features a significantly higher difficulty level overall than its predecessors, as well as a more linear setup with virtually no backtracking or revisiting of previous areas. It also contains a much darker, higher-stakes plot than the previous two games; however, it doesn't sacrifice its quirky humor or enjoyably bizarre setting to do so, so kudos for that.