Libgdx is a game engine written in Java.This is the huge advantage for Java developer who want to make a game in Java.Moreover Kotlin support is also there. With Libgdx you can export to major platforms including ios, Android, Web, Linux, Mac, Windows with a single code base. Libgdx is open source, that implies you can customize, add features to Engine while maintaining your forked project.

LibGDX is at its core a low-level wrapper over opengl. This gives the programmer plenty of flexibility and control in building a game engine. Beyond that, the framework has support for building ui, particle effects, texture atlases, and more. It's also open-source, making it easy to modify as you see fit. Java's garbage collection feature saves some of the hassle of dealing with memory management, but for game development, that garbage collector needs to run as infrequently as possible. Libgdx is fast and its custom java collections implementations are carefully crafted to avoid garbage collections. Libgdx also has several optional plugins to handle features like AI, entity-component systems, and more.

It's high performance and cross platform. The documentation isn't bad be prepared to google & read. The community is great and there are tons of tutorials on the web. If you are willing to put the time in you will learn a ton and possibly wind up with a great game.