Perfect World has posted a note on the RaiderZ Arc page to let players know that the game will be shutting down for good on August 10th. It appears that the game's developer, MAIET, is, or has also, shut down. Without a developer to keep the game running, the post goes on, there is no one to troubleshoot the game, etc.
We will shut down RaiderZ on August 7, 10am PDT. Prior to the shutdown, we will bring back the east servers to working order.
All RaiderZ payments dated back to May 7 will be refunded 100% to your Arc Account Balance, which can be spent in any of our PWE games.
Read the full announcement on the RaiderZ site.