Here are the Eric Mistal landscapes that work in EAW or OP (not SFC3).
http://www.3ddownloads.com/strategy-gaming/sfc/chrisjones/sfcop/landscapes.rarSaturn's Rings
Mars Orbit
Rocky Wasteland
Deep Sea
Cold Landscape
Cochrane City, Mars
Archipelago (Planet Environment)
These instructions are different than normal models.
1. Download Files, and extract it into /Assets/Models/landscapenamegoeshere/
2. Open ShipEdit
3. Create a new ship Class, give it 4999 shields, 127 armour, hull strentgh. Do NOT make it a planet or it will not work. Your ship would insantly be destroyed. NO WEAPONS ON NON-BASE/CITY LANDSCAPES!!!!! Also give in "H" turn rate, and acceleration 0.
4: Save it.
5. Open SFC, and go to Skirmish or Multiplayer. Make sure the Computer has the Landscape on its side, or it will start shooting at it.
6. Start the game, and enjoy!!
I tried this in SFC3 and it would not load the landscape.. looks great in EAW and OP!!!