List of the top Aliens games:

The humanity succumbed against the power of a aliens intergalactic empire, but managed to organize and establish a resistance army. Join the rebellious seekers of peace and help them defeat the evil that haunts the Earth.

The XCOM: Enemy Unknown - Slingshot Pack is Now Available!

Strange radio bursts have been detected! Embark on an immersive adventure as you analyze radio signals coming from space, decipher hidden messages, symbols, sounds, and translate alien languages. Follow an engaging story with countless dialogues and game-changing choices.

There's something evil in the city tonight... Earth has been ravaged by human excess, petty conflict and alien invasion. The world's population has been herded into huge cities, the first of which was Mega Primus. 2084: A Utopia shattered, social collapse and civil unrest reigns in Mega Primus. Fiendish aliens terrorize the city.

The year is 1962 and the Cold War has the nation gripped by fear.  A top-secret government unit called The Bureau begins investigating a series of mysterious attacks by an enemy more powerful than communism.

Experience the explosive science fiction arcade-shooter that resurrects a much revered franchise in an epic single player and co-op multiplayer campaign.

XCOM: Chimera Squad delivers an all-new story and turn-based tactical combat experience in the XCOM universe.

In the game you play the Pandean hero, Tin, which has a mission to save his planet from alien threat. You will be facing many obstacles thru different environments, where you will meet angry robots and funny looking animals.

Halo: Spartan Strike makes you a Spartan supersoldier battling evil forces. Delve into 30 challenging missions through cities and jungles using a devastating arsenal of weapons, abilities and vehicles including the iconic Warthog against the Covenant and Promethean enemies. *DirectX feature level 10 required*

You are in control of X-COM: an organization formed by the world's governments to fight the ever-increasing alien menace.

The game takes place in a nearby galaxy where a fighter with intergalactic evil in the form of a black cat has settled down

Act as an alien driving a UFO and collect materials to upgrade the spacecraft. Kidnap bikini girls, extract purple energy, and study the function of purple energy. Avoid human attacks, strengthen the defense of spacecraft and alien technology.

Defense Grid: The Awakening is a unique spin on tower defense gameplay that will appeal to players of all skill levels. A horde of enemies is invading, and it's up to the player to stop them by strategically building fortification towers around their base.

XCOM 2 is the sequel to XCOM: Enemy Unknown, the 2012 award-winning strategy game of the year. Earth has changed and is now under alien rule. Facing impossible odds you must rebuild XCOM, and ignite a global resistance to reclaim our world and save humanity.

When humanity reached Mars, another civilization got there first. An invasion was imminent. Despite preparations (a defense fleet with a freighter with lots of missiles!), will humanity survive such an advanced invading horde?

An action-packed typing game where you shoot down UFOs, jets, birds and more from your missile base. Unlock special equipment and take part in a dynamic storyline influenced by your targeting choices.

Co-operative multiplayer game and complete code base available for free.

Survivor: Spark is the first episode of a series of anti alien invasion games. It's a classic transcendental third person shooting game!

A first person space exploration game where you investigate the inner caves of an asteroid passing by your planet. Dive into the deeps of the asteroid aboard your ship, collecting information and samples of many beautiful minerals and lifeforms while searching for more complex and intelligent beings

Return to the Black Mesa Research Facility as one of the military specialists assigned to eliminate Gordon Freeman. Experience an entirely new episode of single player action. Meet fierce alien opponents, and experiment with new weaponry. Named 'Game of the Year' by the Academy of Interactive Arts and Sciences.

Stand and fight for humanity. This arcade shooter takes place in the year 2022, as the Earth Defense Force fends off an all-out attack by unknown life forms. Become an EDF soldier, battle against endless hordes of immense enemies, and restore peace to the earth.

A spaceship simulator for aliens, an ever-changing rule discovery puzzle for humans.

An unknown place, an unknown secret base and an unknown robot from another planet! What does he want? What are you looking for inside the base? Will it be destroyed or will it be able to flee? Play in third person with an alien robot who has infiltrated a secret military installation.

Can you survive the alien onslaught? Gamers across the world will now have a chance to play the next chapter in this high-budget, high-quality series.

UFO: Aftermath is a 3D isometric, tactical strategy game with a rich and compelling sci fi story.