Modifying the 2D RPG game that has been discontinued.

It is an open source 2D MMORPG game developed 20 years ago in Java language. The emulator starts when the Serverstart.bat file is run. The game was serviced in Korea, Japan, and Taiwan, and there are versions developed by several teams. But now the whole team has stopped developing. So there are some bugs and I need a feature implementation. I am a fan of classic games. I would like to fix bugs and features. I live in Korea and need a professional with 2D game development experience. More detailed information will be provided via chat.

The version I have is 1.63. The following monsters are implemented in version 2.00 developed by another team. But the logic is slightly different. Their code is also provided for your reference. Please analyze the logic and implement the motion.

1. Add a motion or action of a specific monster.
1) Spartoi: ground hide & rise
2) Harpy: rise & ground down
3) Troll: resurrection & attack
4) Stone golem: sleep & wake up