Slick2D | 2D Java Game Library. Libgdx.
Crystal Space 3D. jMonkeyEngine.org. Interactive Pulp - PulpCore. Applets are back. 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. Also, PulpCore is designed for ease of development with an intuitive API and a smooth, uninterrupted workflow. Is PulpCore the right framework for your project? PulpCore is designed to fix the problems associated with Java applets by providing attractive loading screens, consistent rendering speeds, and a truly portable engine that works across all major operating systems and Java runtime versions. While PulpCore provides a great boilerplate for a game project, it doesn’t include everything you might be looking for.
Compared to other browser-based frameworks, PulpCore has a easy-to-use API, great performance, and it’s built on Java, so it can integrate with a wide variety of existing Java libraries. Get started.