If you don't have any scripting knowledge, you could always have a touch event that sets the players speed if facing left/right, lower speed to 2, and vice versa, depending on which side the marshland is...
Or.
Search in PokemonField,
class PBTerrain, and add your new terrain there.
and search
Events.onStepTakenFieldMovement+, and add
@move_speed=$game_player.move_speed, to set @move_speed to the players current speed.
then I guess wherever you need to, place
@move_speed = number, but make number any other number, I would suggest any number below
4, probably
2.5 to be honest.
So basically.
Search
SootGrass=14, add
Marsh=15 below.
Search
Events.onStepTakenFieldMovement+, and underneath
Kernel.pbSlideOnIce(event), add:
Code:
elsif $game_map.terrain_tag(event.x,event.y)==PBTerrain::Marsh
@move_speed=$game_player.move_speed
@move_speed = 2.5 # or any other number
Search
return PBEnvironment::Sand, add:
Code:
elsif terrain==PBTerrain::Marsh
return PBEnvironment::Marsh
If you wanted an animation create an animation and look up how grass and sootgrass works and pretty much copy one of them to get the effect you want.
Do this or something like this to add new terrain tags.
This is how I would do it, I don't know if this works, it looks fine, if you want encounters on this tile, I'm sure you can work that out yourself.