I've got Eclipse IDE for Java Developers Version: Neon.3 Release (4.6.3)
I loaded LWJGL3, the latest version 3.1.2. I've added it (like here) to a test project (Hello World from lwjgl.org/guide) and it works without setting anything (...like natives...).
Then i added Sling2D (like here) except for setting the Natives Library Location because in the latest version of lwjgl3 there is no natives folder with native<OS>.dll files! It's only 1 folder with only .jar files.
If i run the Hello World test project (from here) I got the following error:
"Exception in thread "main" java.lang.UnsatisfiedLinkError: no lwjgl64 in java.library.path"
I read everywhere I have to set the Natives Library Location to the lwjgl/native folder with the OS-specific .dll files but i haven't this folder!
The answer is: You cant. Slick2D is made to work with lwjgl 2, lwjgl 3 however is way newer than Slick2D and therefore Slick2D does not support using lwjgl 3. I'd recommend you to use the newest 2.9.x version of lwjgl if you want to use Slick2D.
There might be a workaround though see: http://slick.ninjacave.com/forum/viewtopic.php?f=1&t=7095