L2J is an alternate game server for Lineage2. The L2 protocol is reimplemented in the server, so you can play with this server without any modifications to the client (except changing the server IP address). The latest USA live client version is always supported, so don't expect this server to work with the PTS/Korean client.
xBaK is a fan-made remake of the classic Sierra computer RPG "Betrayal at Krondor". It is a game engine that uses the data files that came with the original game by Sierra Online. You must already have your own copy, since the required data files are not distributed with xBaK. The game is still under development. The intro, the option dialogs, and the main game dialog are finished, but the game is not yet playable. Several tools for examining the contents of the data files are also available.