OS: GNU/Linux Debian Squeeze (Stable)
Kernel: 3.2.9
Processor architecture: amd64 x86_64
Java: Java 7 Update 3
After installing Spiral Knights with the downloadable shell script, I tried playing it. Downloading the game went fine, however running the spiral shell script only returns this projectx log. I had the same problem with Minecraft, another Java-based game. Updating the LWJGL files it uses to version 2.8.3 fixed it. I would assume doing the same here would fix Spiral Knights too.
projectx.log:
2012/03/25 02:24:03:541 INFO I$a.b: Logging to '/home/[user]/.spiral (Broken)/./projectx.log'.
Exception in thread "main" java.lang.UnsatisfiedLinkError: /home/[user]/.spiral (Broken)/native/liblwjgl.so: /home/[user]/.spiral (Broken)/native/liblwjgl.so: wrong ELF class: ELFCLASS32 (Possible cause: architecture word width mismatch)
at java.lang.ClassLoader$NativeLibrary.load(Native Method)
at java.lang.ClassLoader.loadLibrary0(Unknown Source)
at java.lang.ClassLoader.loadLibrary(Unknown Source)
at java.lang.Runtime.loadLibrary0(Unknown Source)
at java.lang.System.loadLibrary(Unknown Source)
at org.lwjgl.Sys$1.run(Sys.java:73)
at java.security.AccessController.doPrivileged(Native Method)
at org.lwjgl.Sys.doLoadLibrary(Sys.java:66)
at org.lwjgl.Sys.loadLibrary(Sys.java:82)
at org.lwjgl.Sys.(Sys.java:99)
at org.lwjgl.openal.AL.(AL.java:59)
at com.threerings.openal.q.(SourceFile:207)
at com.threerings.openal.q.a(SourceFile:73)
at com.threerings.opengl.e.(SourceFile:90)
at com.threerings.opengl.n.(SourceFile:55)
at com.threerings.projectx.client.ProjectXApp.(SourceFile:261)
at com.threerings.projectx.client.ProjectXApp.main(SourceFile:234)
Not sure if that's still the same problem:
http://forums.spiralknights.com/en/node/23072
...but if it is, I don't think it'll be fixed... evar :D
Is there a reason you're not using openjre? Works fine for me.
If I remember right, workarounds for using oracles java can be found in one of the threads linked in the thread I linked to here :D
Good luck.