# Help converting projection/coordinates to Google Earth

I'm trying to program a GPS style tracker for a simulation game but I'm having a hard time figuring out how to transform the game's coordinates into Google Earth's.

The game's world is flat and has the following map projection:

http://postimage.org/image/czoi8rxgn/

The game's current position data is:

Long: from -21,600,000 m to +21,600,000 m

Lat: from -10,800,000 m to +10,800,000 m

Centered at 0m, 0m (0,0 degrees)

Distance between degrees is the same everywhere (120,000 m) for latitudes or longitudes.

I believe this is called an equidistant projection?

My problem is this, when using the formulas (180/21,600,000 * X position) and (90/10,800,000 * Y position) the game's coordinates don't translate correctly to Google Earth (like in this picture where red is the actual path in game, white is the path exported to GE)

http://postimage.org/image/im67likq3

I realize that the world in Google Earth is a 3D sphere so there's probably some more factors I need to take into account but since I'm a completely beginner when it comes to cartography/GIS, I'm kind of lost.

Is there a conversion formula I should be using to match the coordinates?