PulpCore is "a free, open source (BSD license) 2D rendering and animation framework for the Java plug-in. It allows Java developers to create modern-looking 2D web games with a strong focus on animation and positive user experiences."
It comes with a variety of simple examples, including the following. I have rebuilt these apps using Eclipse, Ant, and the PulpCore build environment. The build process worked perfectly out of the box.
The following is another of the PulpCore examples. I made some simple changes before rebuilding it. Again, I had no difficulties doing this.
The last is a much more complex example. I have embedded my own open source Xholon software, and an app that uses Xholon, inside of PulpCore. It turned out to be quite easy to do this. PulpCore handles all the Java applet packaging, and provides 2D graphics and the main processing loop. Xholon provides an environment for app-specific objects to interact with each other. The Xholon Bestiary app itself models cats, humans, other beasts, and other objects, interacting in various ways. This PulpCore version lacks the collaborative capabilities of the original, but this will be added back in as I learn more about PulpCore. The Bestiary app takes more time to start because it needs to load the PulpCore, Xholon, and several third-party libraries. PulpCore provides some tools to minimize the sizes of jar files which I have not yet tried.
I've written some additional notes about PulpCore and other Java game software, including links to a number of online PulpCore games.