Assets not listed below are original works by myself (or assets without a proper re-use license). If you find your stuff in Slanforce, but not listed here, or in violation with the license for this work, let me know and I will make the appropriate changes.

• Galaxy background for level 1-10 is from http://www.spacetelescope.org/images/opo1025a/, cropped by me. Credits to NASA, ESA, SAO, CXC, JPL-Caltech, and STScI. Acknowledgment: G. Fabbiano and Z. Wang (Harvard-Smithsonian CfA, USA), and B. Whitmore (STScI) [1]

• Galaxy background for level 11-20 is from http://www.spacetelescope.org/static/archives/images/screen/heic0910e.jpg, cropped and rotated by me. Credits to NASA, ESA and the Hubble SM4 ERO Team [1]

• Galaxy background for level 21-30 is from http://www.spacetelescope.org/images/heic1220a/, cropped and rotated by me. Credits to NASA, ESA and the Hubble Heritage Team (STScI/AURA) [1]

• Unique ID link on title screen, http://findicons.com/icon/457853/id?id=458060 from http://www.wpzoom.com/ [1]

• The shield activation sound effect is http://freesound.org/people/themfish/sounds/34205/ from http://freesound.org/people/themfish/ [1]

• Biohazard symbol on collectable objects from http://findicons.com/icon/558005/biohazard?id=558005 by VisualPharm [1]

• The enemy fire sound is http://freesound.org/people/bubaproducer/sounds/151013/ from http://freesound.org/people/bubaproducer/ [1]

• The Android robot one this page is reproduced from work created and shared by Google and used according to terms described in the Creative Commons 3.0 Attribution License [2] (http://developer.android.com/distribute/googleplay/promote/brand.html)

• The iOS icon on the activity page is http://www.iconarchive.com/show/social-2-icons-by-position-relative/ios-icon.html from http://www.position-relative.com/ [3]

[1] Creative Commons attribution license 2.0

[2] Creative Commons attribution license 3.0

[3] Creative Commons Attribution-ShareAlike 3.0