fr33kSh0w2012: you need the *.GRP files the files that have .GRP at the end and the file with .RTS on the end
.RTS is not needed. For the original game (inc Atomic) you just need the .GRP.
Spartanwarrior117: Also, how do i autoload duke nukem in the properties? so that way i can just click on on the icon and the game will show up? i know gzdoom has this feature, what about this one?
lastly, is the atomic edition same as the mega edition or no? whats the difference between the two?
If you are using just the original game (no expansions) then it should auto load by default. (There's a checkbox on the select what GRP to load window, so click on that first to stop that window from loading up.)
Edit: Uncheck the box called 'Always show this window on startup.'
I assume your talking about Megaton? Atomic is is just a re-release of the original game with an extra episode (kinda like how Ultimate Doom is a re-release of Doom with another episode.) It also came out in 1996.
Megaton came out in 2013. It includes the Atomic version, plus all of its official expansions (D.C, Nuclear Winter, Caribbean.) It has OpenGL support as it uses JFDuke (similar to eDuke) and uses a higher resolution hud compared to the original.
You should be able to take the GRPs from Megaton to use under eDuke.
I prefer using eDuke though, as Megaton was never released DRM free, Also Megaton has now been removed for sale in favour of 20th Anniversary Wold Tour.