Why am I not getting the hidden quest..

Enter through TimeQuest, accept the 15-minute quest, install the game, run it for over 15 minutes, then close it. After that, click 'Complete TimeQuest' and the hidden reward will appear. Summary: Accept TimeQuest, install the game, run it for 15 minutes, close the game, then complete the TimeQuest to get the hidden reward. You need to follow the steps carefully. If you install the game before accepting the quest, the hidden reward likely won't appear.