A .deb is an installer file for debian/ubuntu/linux mint, it is similar to a .msi, but easier to use. It is also similar to a .dmg, but a smidge harder to use.
Just so people are aware, he has cleared this with me before re-posted. I have confirmed this works on Debian and all package dependencies are fulfilled.
Also, a deb is nothing like an MSI :P I'm not sure on dmg files having never really encountered them (never used a mac long enough) MSI installs *everything* a program needs, deb just tells you what you need to install and won't let you instshenaniganshe proam until dependencies are satisfied.
Double-clicking will only work if you have gDebi installed, if you haven't got it and/or don't want it, you can run the following from Terminal: su -c "dpkg -i /path/to/powder.deb" Ubuntu should use sudo instead of su -c