 
  The Anniversary 2025 event, also known as the Throwback event, brought back old worlds from MRCL's history to commemorate it:
This event gave XANA the ability for the first time ever to attack Earth using Towers from other virtual worlds as it could activate towers on the Taiga Replika and Old Lyoko in addition to the regular version of Lyoko. This also made the Superscan capable of detecting activity in these virtual worlds. Old Lyoko and the Taiga Replika were immune to Software Attacks and did not have any cores to destroy.
Players could enter the old version of Kadic using a command block at spawn (they appeared there directly when joining the server during the first week) and explore its city. They could then reach the old factory to find command blocks to act as Programs and then go in the old Scanners room to virtualize directly onto Old Lyoko, linking them to that virtual world. As such, programs such as the Communication Cards on the regular Supercomputer could no longer identify these players.
Lyoko players had the ability to use the Skidbladnir to reach the other virtual worlds through the Network, and the same went for Old Lyoko players using the old Skidbladnir.
Once the event ended, XANA lost the ability to attack outside of Lyoko. However, the Taiga Replika and Old Lyoko stayed available in the Network and can still be accessed to this day, although the old version of Kadic is gone and the old lab and scanners can no longer be used.