The dramatic tactical action of XCOM: Enemy Unknown earned it a PC Gamer score of 87 when it launched back in 2012. You command a secretive band of supersoldiers as they face off against an alien invasion. Kill the enemy, autopsy their remains and then use them to build bigger weapons with which to kill bigger aliens.

It's still great, which is why you should consider claiming a free Steam key for Enemy Unknown. Green Man Gaming have teamed up with the Golden Joystick Awards to give away thousands of keys. All you have to do to get one is...

1. Vote for your favourite games on the Golden Joystick site.

2. Before voting finishes, a special Playfire site will launch dedicated to the giveaway. Once you've signed up there and linked your playfire account to Steam, you'll be able to receive the email with your key.

3. Important: wait until voting finishes on October 23. Keys won't be sent out until after that point.

3. Sit back and plot the demise of the invading alien species.

The offer is available while stocks last, and you have to be 18 to enter. This is the 32nd annual Golden Joystick Awards, and they still hold the status as the biggest public-voted gaming award in the world. The GJ winners will be announced on October 24.