Asset licenses

`game/background/*.{png,xcf}`

`game/ball/*.{png,xcf}`

`game/ball_launcher/ball_launcher.{png,xcf}`

`game/brick/aura.png`

`game/brick/brick.{png,xcf}`

`game/exit/exit.{png,xcf}`

`game/force_field/*.{png,xcf}`

`game/hud/*.{png,xcf}`

`game/paddle/*.{png,xcf}`

`game/tiles//.{png,xcf}`

Author: Hugo Locurcio
License: CC0 1.0 Universal

`game/ball/bounce.*.wav`

Author: aust_paul on Freesound
License: CC0 1.0 Universal

`game/ball_launcher/smoke_puff.png`

`game/ball/{aura,spark,spinner}.png`

`game/brick/spark.png`

`game/goal/{aura,spark}.png`

Author: Kenney
License: CC0 1.0 Universal

`game/brick/destroy.wav`

Author: SanitysPrime on Freesound
License: CC0 1.0 Universal

`game/goal/{close,get_ball}.wav`

Author: manuts on Freesound (cannot find original source)
License: CC BY 3.0 Unported

`levels/*.ogg`

`menu/menu.ogg`

Author: Andrey Avkhimovich
License: CC BY 3.0 Unported

`menu/click.wav`

Author: rhodesmas on Freesound
License: CC BY 3.0 Unported

`menu/hover.wav`

Author: DrMinky on Freesound
License: CC BY 3.0 Unported