Dead Trigger developer Madfinger Games first released its latest zombie-themed shooter, Unkilled, in September. Now that game has released its first major content update, with 20 new story missions and more new content:

Here's a quick summary of the storyline for the additional missions:

In the new missions, our hero Joe works alongside the Resistance to explore a secret research lab that may contain secrets about the origin of the zombie plague. The lab had been operating under the guise of working for the World Health Organisation (WHO), and won't be easy to investigate given the high level of contamination. With the atmosphere so polluted it will be hard to stop and take a break. "

The update also adds the Czech-made assault rifle CZ 805 BREN A1, and includes a new in-game chat feature that allows friends to communicate with each other as they play. Finally, there are plans for a special Halloween event next week, feature new zombies with "huge pumpkin heads". You can download Unkilled right now from the Google Play Store.