Screenshot by Lance Whitney/CNET

Android users can now shout "Avengers, Assemble!" as they team up with Iron Man, Captain America, Thor, and other mighty heroes in a free adventure game.

Formerly available just for iOS and Facebook users, Avengers Alliance launched on Thursday via Google Play. The game signs you up as a new SHIELD agent ready to spy and fight on behalf of Nick Fury. But before you can even complete your training, your first mission arises.

From that point on, you have to recruit superheroes from Marvel's massive lineup to help you vanquish the forces of Hydra as well as such supervillains as Loki and Dr. Doom. As expected, each mission gets more difficult as you're forced to face more fearsome threats. But along the way you can tap into an arsenal of weapons and replenish those heroes whose power has weakened.

Avengers Alliance is not your standard fast-paced shoot-em-up, punch-em-out game. Instead, it proceeds more slowly and methodically as you have to decide which missions to take, how to best use your team's resources, and when to call in the superpowered cavalry. At times, the game also tells you what to do and where to go so you're not completely in the dark.