Age of Zombies

Missable! I'm calling this missable simply for that if you lose all of your lives and use a continue, you will have to restart from the beginning. Note that you CAN put the Vita into sleep mode and walk away from the game, and it will still count as one sitting. You can even use the PS button and go through the XMB without ruining your chance at this trophy. Just make sure you don't close the application, or power off your vita (keep it charged!).