A few things cause this exception:
1) Check if you have all jars and if they're in the correct path.
2) Your classpath might be broken, you can define it in the command line with
java -cp yourClassPath or at your IDE if you're using one.
If you're using Hibernate, this indicates you're missing FasterXML Classmate dependency, which you can add to your dependencies. To add it, the groupId is com.fasterxml and artifactId is Classmate.
java.lang.NoClassDefFoundError: gdxtest/game/MyGdxGame at gdxtest.Launcher.main(Launcher.java:11) Caused by: java.lang.ClassNotFoundException: gdxtest.game.MyGdxGame at java.net.URLClassLoader.findClass(Unknown Source) at java.lang.ClassLoader.loadClass(Unknown Source) at sun.misc.Launcher$AppClassLoader.loadClass(Unknown Source) at java.lang.ClassLoader.loadClass(Unknown Source) ... 1 more