The impending Flood invasion is near! Be very, very, afraid.
Re: Assimilate. Evolve. Eradicate!A after destoying the Alienz, the Avatar decided that they've earned a nap, so they sleep for 69 years. The events of Xeno Tactics begin when the Avatar wake up. They are very hungry, and since the remaining Alienz will not freely offer themselves up as food, war ensues.
The invaders have a hive mind, which allow them to communicate using telepathy, enabling them to formulate attack plans and strategies. Highly efficient killers with the sole purpose of eating all living, the Avatar, now calling themselves The Flood, are a symbiotic species which assimilated millions of hosts throughout the galaxy, on their good ol' days. The invaders are arguably the only things stupider than your average Space Marine. But who needs brains when The Flood can consume entire enemy bases in half the time the Guardians do?
Examples of The Flood structures, evolutions and great warriors
The Flood devours unsuspecting alien organisms with the purpose of assimilating them into the 'Awesomeness'. They are highly selective and chose only the most advanced strains. In that regards, humans are safe... The Flood origins are unknown; some say they were always 'here' because of their sudden appearance from deep underground, as if they were waiting for a sign. It is thought that the sign was the evolution of the intelligent life itself.
Defend That Which Matters The MostAs a Guardian, you will start the game acting as a leader of a Resistance outpost. You and other Guardians are the Altarian elite, the last resort. You are the best! You have seen many suns and planets, even the hidden Terra, which is far from being *just* a legend. But we all need to buy our mother Earth time... Time to rebuild, time to design the Ultimate Weapon that will repel the alien invasion, once and for all.
Until this day, you have fought well within the Altarian forces, but now you're on your own. You've chosen your planet; you've made your arrangements, now it's time to fulfill your destiny. No regrets! The Resistance will be remembered and the Guardians defending the lost Terra with their very lives shall forever live in the memories of your children. For you are... legendary!
Examples of Guardian structures, technologies and Resistance units