For all of you that have bought Eufloria over Steam but don't want Steam to start everytime you start Eufloria:
You can just set a link to the original "Eufloria.exe" and then only Eufloria will start.
You will find it in this folder: ...\Valve\Steam\SteamApps\common\eufloria\Eufloria.exe
Have fun.
FatBaron