[Pyros]

Ok,

First of all, you can't modify the retreat direction to anything else than a left-right axis (if you put obstacles * for example impassable terrain for vehicles, you may force these units to move to a different direction) .

Secondly, since this isn't a beach landing you should make 2 things:

1. From the scenario editor screen you should press the "swap" button on the map sides option.

2. When you design your map at the "map edit" you should press the shift + "$" and you will be asked if you wish to change the status of the map from "beach landing" to "normal" (do this in order to avoid being asked if you wish to buy barges for your units).

cheers,
Pyros

p.s Whenever you create an ocean beach with the "create beach" tool (from the map editor), the status of the map will be automatically changed to "beach assault".