As a thank you to loyal players that have been active over the last three months, qualifying players will receive vouchers for Frogsters Runes of Magic MMORPG that can be redeemed for in-game mounts and Diamonds. Players that purchased Mythos will also receive a Runes of Magic bundle with the same value as the Mythos game box.
According to the post, Mythos did not achieve the "desired long-term success" following a promising launch in April earlier this year.
MYTHOS enjoyed great popularity with the launch in April and the numerous registered users ensured a good start. The desired long-term success unfortunately did not follow. Under these circumstances, we have made the difficult decision to discontinue the operation of MYTHOS.
Source: Mythos website
Update: Mythos Global Heads to Open Beta