1. Try to launch from the spiral knights website, through firefox (safari didn't work me)
2. Let it download and patch and everything
3. Go to the java website to test what version you have (WILL NOT WORK ON CHROME)
http://www.java.com/en/download/installed.jsp
4. Follow the oracle instructions on uninstalling java 7
(You do not need to use terminal. Disregard the bottom half of the instructions)
http://www.java.com/en/download/help/mac_uninstall_java.xml
5. Follow the apple instructions on how to re-enable java 6
http://support.apple.com/kb/HT5559?viewlocale=en_US
6. Restart browsers and try to relaunch
NOTE: IF THIS DOES NOT WORK FOR YOU, FOLLOW THE FOLLOWING STEAM USER INSTRUCTIONS NUMBERS 1 AND 2, RESTART YOUR BROWSER AND RELAUNCH.
Steam users - follow above and following instructions
1. Open two separate finder windows, and locate to "DRIVE NAME"/Library/Java/JavaVirtualMachines and grab the "1.6.0 jdk" folder and copy it.
2. Then on the other finder window, locate to "DRIVE NAME"/System/Library/Java/JavaVirtualMachines and copy that folder to there and delete the existing "jdk1.7.0_25.jdk" folder
3. Validate the files on steam by going to your games library on steam, right clicking on Spiral knights, selecting properties, go to the local files tab, and then click "Verify Integrity of Game Cache"