Planertary Invasion

[Lord Kodos]

infact here are some of the Scenarios even:

Hive Cleansing:Use your team of elite Vectorian Marines to destroy a Swarmer Hive.

Intel Procurement:You play as a young terren spy during the Corparate Wars on earth.You must infiltrate an enemy complex,Procure the prototype Tank and escape with it.

JUST samples there is much much more

Quadrent Types:
Planet:There will sub types
Ship:Same as above

[Suicide Junkie]

Most things can be made out of a color-replace of that grass one. Green->brown->blue->yellow(sandy)

We could try tracing some from a FPS game, too... (IE: not a screenshot, but a hand drawing of the same style)
some quickies

And, when pasted together:

[Lord Kodos]

gee thanks sure!how about for metal though

[Suicide Junkie]

Metal is not often found in large quantities.
Except on a ship, maybe.
What scale are you planning to use for these metal images?
You can't very well make a corridor that is 1 sector wide, unless you're really doing some funky matrix style action with ships or drones being bullets that fly to their targets.

Some example uses are nessesary, or I won't know where to begin with the metal images.