also convert/pngcrush png pictures with 16bit/channel (resulting in 8bit/channel) and repage their layers (as I found out that some of the pics had their layer offset the actual visual area, which makes the picture look blank in gimp)
foreach(dir
Bamboo
BambooPlinko
Basketball
Bath
Battlefield
Blizzard
Blox
Bubbleflow
Cake
Castle
Cave
Cheese
Cogs
Control
CrazyMission
CTF_Blizzard
EarthRise
Eyes
Hammock
HedgeFortress
Hedgelove
Hedgewars
Hogville
Hydrant
Islands
Knockball
Lonely_Island
Mushrooms
Octorama
PirateFlag
Plane
Ropes
Ruler
Sheep
ShoppaKing
Sticks
Trash
Tree
TrophyRace
)
add_subdirectory(${dir})
endforeach(dir)