D1ver, HumbleBundle too?
BTW, you can manually make a Slack package out of most .deb files and it is not really complicated. .debs have one particular file you should be interested in: data.tar.gz. They keep their doinst.sh in another file called control.tar.gz which you should inspect and, if needed, incorporate into a post-install script.
In the case of SpaceChem, you can do the following:
mkdir -p work/pkg
ar -x /path/to/SpaceChem-i386.deb
tar xvf ../data.tar.gz
Then, as root, you run makepkg in the work/pkg directory, like
makepkg -l y -c n /tmp/SpaceChem-i386.txz