@Latch-
That is very true, and the solution you offered wouldn't require purchasing version 1.13. Now, back to work on your collision DLL!
@anon-
If the customer expects the game to be able to be run off of the DVD, you could just have the executable placed in %TEMP% every time the DVD is inserted.
It is very easy to copy a file in C, and you can compile the program in Tiny C Compiler, or you can use FreeBASIC to do the same thing, or you can use AutoHotkey (although it might return a false positive in some antivirus programs), or you can write a batch file (although it would make a console window come up), or you could simply write it in js or vbs if you want to learn the Windows Script Host.
After the program is copied, your little launcher program should run it. It's better to have an automated solution like this than an installer, especially considering the fact that DarkBASIC places temporary files anyways. Your customer won't get mad if he finds a copy of his favorite game in his temp folder.
By the way, you should consider keeping all of your media on the DVD and just copying over the executable, as you write the absolute path of the media to a registry value. It seems faster if the media is loaded at load time than if it is copied while the customer is wondering why nothing is coming up on the screen.