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>Type changes
Fairy type removed
Rock type fused with Ground type to make Earth type
Sound type added
>Region lay out
First 2 and last gym are in order. 3-7 are non-linear. The only limiting factor is that to progress to the final gym town, you have to progress through 3 cities, each requiring 2 to move on to the next city, with the final only needing one to reach the final gym.
There are several side routes that you can explore, mostly leading to you finding the location of a new legendary, a valuable TM (Flamethrower, EQ, Protect, Substitute, etc), or a new city.
>Gyms
Each have their own, unique puzzle. First 2 are piss easy, but 3-7 ramp up the difficulty drastically. The gym trainers Pokemon are all leveled 34-37, minus 4 levels for every badge you don't have. This means you could challenge any gym, in any order, and that way you can plan your path through them based on your team's evolution levels.
>Extras
Battle Frontier is in with all 12 facilities from all of the Pokemon games (The 7 from Emerald + 5 from Platinum/HG/SS). Tons of legendaries for you to hunt.
Once you beat the E4, there is a hidden route somewhere that opens up to a training ground city. This city has the IV rater, and a new NPC that lets you change your Pokemon's nature to something else of the same stat category (Say, Timid Mienshao to a Jolly one, since they're both +speed). The city also has wild Pokemon, much like White Forest, and each patch of grass has increasingly higher level of Pokemon, one for each stat type (level 5 grass has 6 different Pokemon, each giving 1 EV of HP, Attack, Speed, Special Attack, Special Defense, or Defense. Level 45 grass Pokemon give +3 to their respective stats).
>Marketing
Tease only the first forms of the starters, and the two main legendaries. Worldwide release date, meaning no sneaky Wops or Canucks. You can pre-download the game digitally up to a week before launch if you've pre-ordered it, that way you can play as soon as the launch date hits.