What mechanic in Angry Birds Space alters bird trajectories?

The Angry Birds Space mechanic that alters bird trajectories is gravity wells.

Angry Birds Space replaces the mostly flat levels of earlier games with planetoids surrounded by gravitational fields. These gravity wells pull launched birds and other objects toward a planet, bending their paths into curved trajectories. Players must use that motion to reach pigs, loop around planets, or approach structures from unexpected angles.

The mechanic gives Space its central identity. In ordinary Angry Birds levels, the bird follows a largely familiar ballistic arc. In Space, launch speed and direction still matter, but the nearby planets can redirect the bird after launch. A successful shot may involve using one planet’s gravity to sling the bird toward another target rather than aiming directly at it.

The game was developed and published by Rovio Entertainment and launched on March 22, 2012. It also introduced new space-themed birds and environments, including Ice Bird. Teleporters, boosters, and wind tunnels may sound plausible because later levels contain unusual effects, but they are not the defining trajectory mechanic described here.