AZI : ALIENS ZOMBIES INVASION Windows, Linux game

A Zombies Army landed on earth, soon followed by droids, creatures and space ships heavily armed.We quickly realized that they were using a zombie manufacturing technology by a bio-technological process combined with a terrifying virus.We lost. But a small group of soldiers and scientists decided to try one last time to end this invasion. Who are they ? What do they want ? Where are all these people who have disappeared ?