This game has the ability to be modified.
You can change sprites, sounds, musics and even the rules!
To create a mod, first you gotta have to create a folder in the RTSData folder.
Name your folder as you wish, for example: mymod. After that, duplicate the file
KILLERS.mdf to the same place and change the name KILLERS to the same exact name of the new
folder. Now go to folder main and copy the file rules.ini to your mod folder. 
till now you got a folder named: mymod, a file named mymod.mdf and another copy of the file
rules.ini. Now lets mod!
If you want to change sprites, first create a folder named Graphics in your mod folder and
then go to the folder Main\Graphics and pick an image, then copy it to your Graphics folder
and edit the file there with Paint program or whatever you want to with but don't touch
the file name! Now whenever you'll load this mod with the Mod Selector which is in the game's
folder, you'll notice that the sprite you've modified is shown there! Now it's the same with
Sounds and Musics. To change the game's rules, you need to edit the rules.ini file that is
in your mod folder.
For example:
to change the speed of the commander, you look for the headline [Commander] and below it
you can find his details and change it:
the original:
healthp=5.5
speed=2
The edited:
healthp=10
speed=4

This is it! If you find it complicated, then you should wait till the SDK tools will be released!