It's a turn-based strategy game that:
(...) combines childhood memories of backyard play with whimsical artwork and combat strategy mechanics of a digital collectible card game (CCG). Allowing for both creative and strategic gameplay, Backyard Battles is easy to learn, difficult to master – and a whole lot of fun.
It's everyone's childhood dream come true as neighborhood kids arm themselves with broom handle swords, PVC pipe cannons and tennis racket magic wands to attack and defend their cardboard box forts. Playing either single- or multi-player matches, users take turns placing their heroes on a three-lane backyard board and compete for victory.
The playful features:
• Bring Out Your Inner Child – Backyard Battles brings childhood memories to the digital age on mobile devices and browsers. Each player has to defend a cardboard box fort behind their team of heroes, using creative weapons crafted from everyday items found in their parents' attics, closets and garage.
• Easy to Learn, but Difficult to Master – Though deep with collectible card game (CCG) strategy game mechanics, Backyard Battles leaves plenty of room for room for players to be creative. Each player defends their team's cardboard box fort and takes turn placing their heroes and items in a three-lane battlefield in one-on-one matches. On each turn, they can choose from an assortment of heroes and weapons that are included in the selected squad.
• Balance is Key. No one squad is tougher than another as balance is a key factor in Backyard Battles. Players can customize heroes and items to be included in different squads. They might choose to go with all power while another can focus on defensive heroes and items, all while carefully anticipating their opponent's next move.
• Asynchronous Multiplayer and More – What is a strategy game without multi-player action? Backyard Battles features asynchronous multi-player over Wi-Fi and LTE, as well as play-and-pass style multi-player mode for some in-your-face gaming. The game also includes single-player challenges
From recent PAX Prime coverage by Polygon we further learn:
There are currently upward of 20 heroes in the game, with each hero having different abilities. Co-founder and CTO of Naked Sky, Joshua Glazer told Polygon that the game currently has the robot hero class (which is represented by a kid in a cardboard box), a pirate, knight, sniper, fairy, dragon, fireman, businessman and hacker. Players will be able to build their squads from any combination of heroes, and they will also be able to build different forts to match different squads.
The developers are being secretive about a specific release date, toying with "later this year" for now, so I guess we'll just play along and await their cheery proclamation about when the fun really is to begin.