We thank the creators of the different sound files:

sound_item_preventcreaturebuilding.mp3
http://soundbible.com/1722-Cordless-Drill-2.html
Uploaded: 08.02.11 | License: Public Domain | Recorded by Mike Koenig

sound_button.mp3
Created: 25.03.11 | License: Creative Commons Universal Waiver  / CC0 | Created by Frederic Kerber 

sound_item_towerkill.mp3
Created: 25.03.11 | License: Creative Commons Universal Waiver  / CC0 | Created by Frederic Kerber 

sound_item_ultima.mp3
Created: 25.03.11 | License: Creative Commons Universal Waiver  / CC0 | Created by Frederic Kerber 

sound_item_creaturekill.mp3
http://soundbible.com/1394-Dragon-Bite.html
Uploaded: 12.03.10 | License: Public Domain | Recorded by Gregory Weir

sound_levelup.mp3
Created: 25.03.11 | License: Creative Commons Universal Waiver  / CC0 | Created by Frederic Kerber 

sound_item_creaturefreeze.mp3
http://soundbible.com/135-Cracking-Peanut-Shells.html
Uploaded: 05.05.09 | License: Public Domain | Recorded by Mike Koenig

sound_item_exp.mp3
Created: 25.03.11 | License: Creative Commons Universal Waiver  / CC0 | Created by Frederic Kerber 

sound_item_decreaselevel.mp3
http://soundbible.com/984-Striking-Match.html
Uploaded: 09.09.09 | License: Public Domain | Recorded by Mike Koenig

sound_leveldown.mp3
Created: 25.03.11 | License: Creative Commons Universal Waiver  / CC0 | Created by Frederic Kerber 

sound_item_preventtowerbuilding.mp3
Created: 25.03.11 | License: Creative Commons Universal Waiver  / CC0 | Created by Frederic Kerber 

sound_item_armageddon.mp3
Created: 25.03.11 | License: Creative Commons Universal Waiver  / CC0 | Created by Frederic Kerber 

music_badwins.mp3
Created: 25.03.11 | License: Creative Commons Universal Waiver  / CC0 | Created by Frederic Kerber 

music_draw.mp3
Created: 25.03.11 | License: Creative Commons Universal Waiver  / CC0 | Created by Frederic Kerber 

music_goodwins.mp3
Created: 25.03.11 | License: Creative Commons Universal Waiver  / CC0 | Created by Frederic Kerber 

music_menu.mp3
http://www.artistserver.com/artist/song.cfm/a/17582/tid/15728/Larry_Allen_Brown
Uploaded: 02.11.06 | License: Public Domain | By: Larry Allen Brown

Moreover we thank Marcel de Jong (www.marceldejong.com) for his nice font 'Fairydust B'.