Mother 3.5 is a heavily modified version of Mother 3 written by Portal-Kombat (t∣b∣c). Although many elements of the classic original remain, there are differences in that the game is 3D instead of 2D (and on the GCN as opposed to the GBA), features a much larger world, different story layout, many added enemies, characters, and PK powers as well as a day/night system.
Enemies are still encountered the same way- you come into contact with them in the overworld. There are still 16-hit combos although there are many new battle songs. Also, you can encounter more than three enemies at a time now. Some PK powers can be charged up by doing music combos as well this time. Also, there are still rolling counters and smashes, and this time you can even smash multiple times during combos. One important feature is that the rolling counters can be saved at zero, like in the real EarthBound (Mother 2).
The Nowhere Islands were the special islands where the story of Mother 3 takes place. In Mother 3.5, the island looks very different. Instead of one large main island and a smaller one, there are a few more islands. In this game the Nowhere Islands almost seem like some kind of parallel-universe Hawaii. At first only the starter island is open for exploration, but as the story progresses, your party can explore other islands as well.
The same basic elements of Mother 3's story are kept intact, but there are several differences in the way the chapters are presented. For example, the Prologue of the game is playable, and it is nearly identical to the prologue of Mother 3. However, after the prologue there aren't any real "chapters" per se, the game's story just unfolds over time. Instead of getting through the original first three chapters of the game, the story starts off around the "chapter four" mark from the original game. In other words, Lucas will always be the main playable character. From that point, the story unfolds around Lucas' efforts to foil the mysterious plans of the Pig Army that appeared on the Nowhere Islands three years ago. Along the way, Lucas learns about the murky past of the world, the Pig Army's plot, and the truth about the Seven Needles, which is this time heavily influenced by the biggest change in the story, PROJECT DARKDRAGON.
Main characters remain from the original. However, Duster and Kumatora aren't introduced until slightly further into the story. The villagers from Tazmily Village are still there, although they live in different houses. There are many new NPCs out there to find though with trademark funny lines of dialogue. There are mysterious characters in Mother 3.5 which seem to be this game's version of the Mother 3 Magypsies. They are called Cavemen and they are recluses that hide away in the dark corners of the islands. The reason there are "Cavemen" instead is integral to the new plot.
The Pigmasks are the main enemies and are encountered much more frequently than in the original Mother 3. The chimeras are also a constant nuisance. Although many old enemies and bosses are gone, there are tons of new ones, including bosses. Actually, there are also a few antagonist characters that you'll fight on multiple occasions, more so than in Mother 3, like the Fierce Pork Trooper, Fassad and even Mr. Genetor. Enemies are listed in Mother 3.5 Enemies.
Although there were "dungeons" in Mother 3, it is more clear what places are dungeons in this game. They are:
- Nova Canyon Temple
- Thunder Tower
- Abandoned Factory
- Discovery Laboratory
- Empire Porky Building
- Caves of the Future
The same PK Abilities from the original return, although this time PK Love is called PK Rockin' in honor of EarthBound/Mother 2. There are many new returning ones, but those are a surprise. You learn them periodically depending on your current level, but some are also learned through set or secret events. Also, when you have a PSI fever, you won't slow down. You can still run. HP and PP can still be replenished in hot springs, but these are often more difficult to find.
Day and Night
Gradually, day becomes night. This causes various changes, like roads sometimes being blocked off or opened up, different NPCs and enemies and things like that. It's nothing too game-breaking, but it feels like time is passing in the world.