I think it's worth noting that DN II lies to you when it says it's saving the game, because you have to properly
exit the game (eg, quit to the main menu, and then exit to DOS) in order for the save to persist. So if you save the game and then quit the game by quitting DOSbox instead of quitting via the game's menu-prompts, you'll lose your save.
This bit me in the ass when I was playing through DN II a little while ago, and I lost a substantial amount of progress. Although, luckily, I figured-out the save file format and how to edit a save to take me to any level I want.
If you want to go this route and edit what level you're on:
1) Start-up DN II in the chapter you want, save the game, and then properly exit the game. After you do this, you should see a file called "NUKEM2.-S1" (where '1' represents the save-game slot). This is your save-game file.
2) Download a hex editor, such as HxD
3) Open the save-file in the hex editor, and navigate to the offset 0000000A
. To do this, just hit Ctrl+G and copy/paste that value into the dialog box. Hit 'OK'.
4) This offset in the save-file represents what level you are currently on. It should currently be on '00' if you saved on the first level of the chapter, since it counts-up from zero.
00 = level 1,
01 = level 2,
02 = level 3,
Let's say you want to go to the sixth level of a chapter. To do this, you would go to the offset we mentioned earlier, and then type: 0 5
. After you've done with, save the file, and you should
be good to go when you next load that save in DN II.
Here is a screenshot
of what I just detailed. It shows what value should be entered into the Ctrl+G offset dialog I mentioned earlier, and the value at 0000000A
being edited to 05
, which means that we will be on the 6th level when the save is loaded.
Let us hope this post has been useful.