Aksys Games and Japanese developer Acquire have launched Aegis of Earth: Protonovus Assault for PC via Steam.

The game is currently available at a 20% discount, at $15.99 down from its regular $19.99 price.

The game has been available in English on PlayStation 3, PlayStation 4, and PS Vita since March of this year.

You can find a refresher on the game below, via Aksys:

A frenetic and explosive new spin on action strategy gaming. Plan out and build up your defenses as hordes of hulking monstrosities bombard your heavily fortified city in an attempt to wipe you off the Earth for good! Command the last bastion of humanity as you fight for the survival of the species utilizing fantastic tech, cunning tactics and massive weapons in an all-out action strategy extravaganza!

Key Features:

• Defense is the Strongest Offense
  Engage in dynamic city defense via revolutionary gameplay mechanics in which you rotate your entire city to aim weapons and take out monsters! Leave no quadrant untouched as you spin 360 degrees in search of would-be destroyers!
• Immersive Commander Experience
  Command and level up a huge variety of units and gargantuan weapons as you hone your tactical skills. Immersive gameplay puts you in the center of intense combat. Seize the initiative from your enemies and decimate their ranks as a robust cast of characters lend their support to the cause!
• Massive Content Keeps You in the Fight!
  An intense 20+ hour campaign ensures you’ll have your hands full as you battle through 23 epic missions! Fend off 15 species of relentless enemies that will not stop until your city is reduced to rubble!