Angry Birds 2 Adds Bosses and Ditches Premium Model

The enduringly popular mobile game Angry Birds has gotten a sequel in the form of Angry Birds 2, which launched today across iOS and Android. The core gameplay remains unchanged--you still fling birds at dangerously unstable structures in order to destroy pigs and reclaim eggs--but in addition to a graphical upgrade, developer Rovio has introduced a few big changes as well.

For one, the game is now entirely free-to-play. Unlike previous versions of Angry Birds that offered either a premium game or an ad-supported version, there's only one Angry Birds 2. Instead, your arsenal of birds takes the form of cards, and when you use them up, you lose a life. In typical free-to-play fashion, you can either wait for those lives to refill after using them up, or spend in-game currency to buy a few more chances.

Stages have a new, multi-area layout, and you start each stage with just a single card for each of the game's birds. You can freely choose which bird you want to use at any given time, and you can earn a bird back by causing more destruction. That means that doing well in the game lets you play continuously and without interruption. But it also means that just doing OK and barely clearing a part of a level, but using all of your birds to do so, may leave you with and empty arsenal and a "game over" screen.

Angry Birds 2 also adds a new boss mechanic. These more resilient pig opponents take a lot more damage and require a little more strategy than the typical enemy, as shown in the gameplay video above.

There's only one type of currency in the game, gems, which can be earned by completing daily challenges or by paying real-world cash. That currency allows you to buy a second chance in a stage you fail or to purchase consumable spell cards that cause a large amount of concentrated destruction in a stage.

The change to a more traditional free-to-play model may draw some criticism from hardcore fans, but the move is unsurprising given the surge in users that games like Plants vs. Zombies 2 experienced after switching from premium to free-to-play.

Angry Birds 2 launches today across mobile and tablet devices. The game includes multiple worlds and hundreds of stages to complete; additional worlds will be added to the game over time.

Previous Angry Birds games have had console releases as well, and, while developer Rovio has not ruled that out as a possibility for this sequel, a representative for the company told GameSpot that the current focus is on mobile platforms with no immediate plans for release on other platforms yet.