Unfortunately Mint Software Center is not the Ubuntu Software Center. Mint uses Ubuntu respositories. Applications and Games "sold" (whether free or not) are not
in the standard repositories and therefore only in Ubuntu Software Center.
If you use any flavor of Ubuntu (Kubuntu, Lubuntu, Xubuntu, Mint, PinguyOS, etc...) the installation of Ubuntu Software Center is as easy as
sudo apt-get update
sudo apt-get install software-center
As far as the other Linux applications go, Xiphos is truly an amazing product. Not quite as feature rich as BA though. For me BA is the only place I can get great premium modules, that I know are practically guaranteed to be as conservative as possible.
For instance, BA is the only place on Earth where you can get "Understanding The Bible Commentary" in software form. I'm pretty sure it's the only software module for any bible program that has every one of these features: Dispensational in theology, Pre-Trib Rapture, Pre-millennial, King James/traditional-text based, Baptism by immersion, Six-day literal creation, Literal in hermeneutics, Concise style of writing,
Discreet use of original languages. Say what you will about your belief in these areas, but to get one source that clearly lays out all of the beliefs is hard to find. Now if only I could afford it.