what is the difference between RTP and non-RTP?
RTPs, otherwise known as (RPGM Run Time Package), are graphics, audio, and other files that are shared among RPGM engine games. If you have the RTPs installed, then it significantly reduces the file size of those games as it doesn't need to include those files as well. If you don't have the required RTPs installed for the version of the RPGM game, then you can either just get those RTPs or you have to get the version of the game that also includes the RTPs with it.
See this webpage:
You must be registered to see the links
. From there, you can (if you want) pick up all the different RTPs for the various versions of RPGM engine games. Just install them somewhere in your directory such as
RPGM RTPs or something. They aren't games, but a shortcut to reduce RPGM games sizes and those games should, of course, should be installed in their own respective directories where you run the executable to play them (as normal). Hope that helps! Cheers!