Gosztyla prefers interpersonal communication over digital alternatives like Twitter or email, and to bring this physical-space philosophy to his game, he had to make it as accessible as possible. This means getting Dual to work across iOS and Android, so a player with an iPhone can shoot space rockets onto the screen of a friend who has a Galaxy S II, for example. He did it, but he says it was difficult. This cross-platform play is only available via WiFi, while two of the same-OS devices can also connect over Bluetooth.
"As far as I know, iOS and Android cannot talk to each other over Bluetooth," Gosztyla says. "One of the biggest challenges I wanted to tackle early on was to get the networking to feel smooth and consistent. I spent a good deal of time working with different networking models, adjusting for lag, and making sure bullets travel through that small gap between the start of each screen when you put two phones side by side."
Not that the phones have to be right next to each other -- players need to stay in range of the WiFi or Bluetooth connection, but otherwise they're able to move as far apart from each other as they wish. Dual has two play styles: a competitive mode called Duel and a cooperative mode called Defend, plus three separate ships with different abilities built to pew pew pew all of your friends.
When Dual launches on April 2nd, it will be free, but that download includes only Duel mode and one ship. A one-time in-app purchase of $1.99 unlocks the full game, and if one person has the whole thing unlocked, a free-version friend can still play Defend with them. Figuring out this pricing structure was tricky, Gosztyla says:
"I'm really not a big fan of free-to-play games or ads, but I couldn't get myself to put a price on a game that you can't play by yourself. Even when a game is $0.99 (less than a cup of coffee), I don't personally feel comfortable asking friends to buy it just so they can play with me, in case they don't enjoy it. I wanted this game to be easily accessible for anyone that got asked to just pick up and play."