Most games available in the App Store will take advantage of an iDevice's entire screen. Though the resulting effect is good, one downside to full-screen apps is that users can't easily check on the time while playing - instead, the game must be paused, and Notification Center must be dragged-down and invoked in order to reveal the time digits that sit at the top of the iDevice's screen. As this is something of an inconvenience, one jailbreak developer has decided to come up with a solution in the form of a jailbreak tweak called NCTabClock.
Once downloaded and installed, this simple tweak does one thing: it adds the aforementioned time digits to the Notification Center tab. Therefore, with NCTabClock enabled, all users have to do to view the time in a full-screen app is to drag down the Notification Center tab. Take a look at the walkthrough video provided by Jailbreak Nation:
Currently, NCTabClock is available in the Cydia Store for free. If you think this jailbreak tweak might be a great addition to your jailbroken iDevice, launch the Cydia app and search for NCTabClock now - you'll find the package in the BigBoss repository.