Main engine file is in `JavaProjectTemplate.java`. If you choose to rename this file you should probably have your IDE refactor it so all references change accordingly. Better to just leave it as-is.
You will find all possible drawing features under the `game` Panel object that is initialized for you. Draw commands all start with `Draw`. The example program contains quite a few of the possible draw commands available.
Mouse input is handled from the `Mouse` static instance. Can poll for `Held`,`Pressed`, and `Released` status of the mouse.
Keyboard input is handled much the same way with the `Key` static instance. Also has `Held`,`Pressed`, and `Released` statuses per key. Keycodes come from the Java Swing `KeyEvent` class (ex.`KeyEvent.VK_UP`).