Here i made few samples of map (source is: WGS84 web UTM projection)
with changed projection (here we can try to crop this samples)
and try to see this sample in game. After that i can make raw image map (cuted)
and raw DEM (H-map) cuted also.
(http://i47.photobucket.com/albums/f158/Xeo_the_Fox/2016-09-19_05-20-03_zpspl0s8j2n.png)
(http://i47.photobucket.com/albums/f158/Xeo_the_Fox/2016-09-19_05-20-56_zpsv6q8ttbg.png)
(http://i47.photobucket.com/albums/f158/Xeo_the_Fox/2016-09-19_05-21-35_zps4dwl8u1j.png)
(http://i47.photobucket.com/albums/f158/Xeo_the_Fox/2016-09-19_05-22-08_zpsrfoosryp.png)
(http://i47.photobucket.com/albums/f158/Xeo_the_Fox/2016-09-19_05-23-52_zpsyu8coiko.png)
(http://i47.photobucket.com/albums/f158/Xeo_the_Fox/2016-09-19_05-25-15_zpseaqvavoz.png)
(http://i47.photobucket.com/albums/f158/Xeo_the_Fox/2016-09-19_05-26-28_zpsdjrc0mgd.png)
(http://i47.photobucket.com/albums/f158/Xeo_the_Fox/2016-09-19_05-27-17_zpssyf5h2sd.png)
Here some test of croping maps (http://exilian.co.uk/forum/index.php?topic=4729.msg109472#msg109472) (just for test) without rotation:
8 samples of projection
(http://i47.photobucket.com/albums/f158/Xeo_the_Fox/aitoff_zpsvpmr4lln.png)
(http://i47.photobucket.com/albums/f158/Xeo_the_Fox/eckert_zps8cldhfc0.png)
(http://i47.photobucket.com/albums/f158/Xeo_the_Fox/utm_zpsso03pxvt.png)
(http://i47.photobucket.com/albums/f158/Xeo_the_Fox/winkel_zpsdg9gtwtp.png)
(http://i47.photobucket.com/albums/f158/Xeo_the_Fox/sinusoidal_zpsyjr8mt90.png)
(http://i47.photobucket.com/albums/f158/Xeo_the_Fox/hotine_zpsykpahl8o.png)
(http://i47.photobucket.com/albums/f158/Xeo_the_Fox/G-D_zpsnumw3yjv.png)
(http://i47.photobucket.com/albums/f158/Xeo_the_Fox/mollweide_zpsnhl5mkup.png)
if we will use GIS it will be two paralel map: game map and modern map.
And it will be real coordinates for game map. And as i say before we
can make third duplicate of map for Google Erth (for example)- it simplifies our work.
Here some test with samples. Two projection: sinusoidal & hotine
sinusoidal
(http://i47.photobucket.com/albums/f158/Xeo_the_Fox/si1_zpsy4r20to6.png)
(http://i47.photobucket.com/albums/f158/Xeo_the_Fox/si2_zpsjofytzf9.png)
(http://i47.photobucket.com/albums/f158/Xeo_the_Fox/si3_zpskgjynnqn.png)
(http://i47.photobucket.com/albums/f158/Xeo_the_Fox/si4_zpskjsde2zu.png)
hotine
(http://i47.photobucket.com/albums/f158/Xeo_the_Fox/HO1_zpsyauf9l61.png)
(http://i47.photobucket.com/albums/f158/Xeo_the_Fox/HO2_zpsi7lhbaie.png)
(http://i47.photobucket.com/albums/f158/Xeo_the_Fox/HO3_zpsxn79ogbz.png)
(http://i47.photobucket.com/albums/f158/Xeo_the_Fox/HO4_zpsed2wre2i.png)
This is a one of simples ways.
If we will use real projection for preparing for editing map. We can rotate image.
We need make some color grid (in gis) like here (grid borders make like size of the game map):
game map border (rotated)
(http://i47.photobucket.com/albums/f158/Xeo_the_Fox/2016-09-20_03-05-48_zpswalazqka.png)
after make KMZ file (of this color grid) for Google Earth. It will be helper for editing game map.
game map border (grid) in GE
(http://i47.photobucket.com/albums/f158/Xeo_the_Fox/2016-09-20_03-07-00_zpsbstoo0fa.png)
The GIS we need only in start (when we make croping and rotaing) after that we need graphical editor (for example photoshop) and google eart.
And we can make easy corection, editing, search etc.
one point in GE and Photoshop
(http://i47.photobucket.com/albums/f158/Xeo_the_Fox/2016-09-20_03-24-59_zpscbot0od7.png)
Prepare ( rotate & crop) Hi-res map also ;)
After we can (without problem) rectify radar, h-map, disasters, faction borders, etc maps and put it in Google Earth :)
I try to make modifycation of projection (Hotine). And made few prototypes for RTR (new PRJ files) in ArcGIS.
Maps don`t need to rotate.
Prototypes of RTR_projection:
(http://i47.photobucket.com/albums/f158/Xeo_the_Fox/hotine2_zpso64nn7dm.png)
(http://i47.photobucket.com/albums/f158/Xeo_the_Fox/hotine3_zpssbe4dvfg.png)
(http://i47.photobucket.com/albums/f158/Xeo_the_Fox/hotine4_zpsqfkqelat.png)
(http://i47.photobucket.com/albums/f158/Xeo_the_Fox/hotine5_zpsp8r8es41.png)
(http://i47.photobucket.com/albums/f158/Xeo_the_Fox/hotine6_zpss8idsvvf.png)
(http://i47.photobucket.com/albums/f158/Xeo_the_Fox/hotine7_zpsydewfe4h.png)
(http://i47.photobucket.com/albums/f158/Xeo_the_Fox/hotine8_zpsikkgll2j.png)
Here (in my cloud) (https://yadi.sk/d/Nzu3kGv7vRrEF) PRJ-files, images from spoiler & images with not cuted (borders) in PSD file.
If you are interested, or some problems then contact me.
P.S.: Different sources (modified projection)
(http://i47.photobucket.com/albums/f158/Xeo_the_Fox/r1_zpswa9qm7o6.png)
(http://i47.photobucket.com/albums/f158/Xeo_the_Fox/r2_zpsosfvyfag.png)
(http://i47.photobucket.com/albums/f158/Xeo_the_Fox/r3_zpsuigpgomw.png)
(http://i47.photobucket.com/albums/f158/Xeo_the_Fox/r4_zpsav0amaj1.png)
(http://i47.photobucket.com/albums/f158/Xeo_the_Fox/r5_zpsjpve0lfl.png)
(http://i47.photobucket.com/albums/f158/Xeo_the_Fox/r6_zps2vd0xl7w.png)
(http://i47.photobucket.com/albums/f158/Xeo_the_Fox/r7_zpscsrgebfb.png)
(http://i47.photobucket.com/albums/f158/Xeo_the_Fox/r8_zps8o07iekx.png)
looks good! I will help with Central Asia region.
Important to show Zhanadariya river in game map (for Chirik-rabad city) it can be dried on the SW or wade ca be there
Kuandaria river not so important, but in this region it can be obstacle to army traffic :
(http://i47.photobucket.com/albums/f158/Xeo_the_Fox/map11_zpsjgj6lsvy.png)
And near Balkhash lake: red -Important, yellow - secondary importance (secondary - not so importan but will be good if pisible to show :
(http://i47.photobucket.com/albums/f158/Xeo_the_Fox/2016-09-28_03-16-22_zps7oqzmpbm.png)