I'm a huge Python fan.
Linux folks shouldn't have any issues with version differences. It's trivial for Linux users (using any reasonable Linux distro) to have multiple Python versions installed.
Before you pick the version of Python to use, make sure the extensions you want to use work with it. It can be non-trivial to recompile extensions for Python -- especially for Windows.
I'm specifically a Python 3 fan. The fixes put in place for Python 3 are useful and important for the growth of the language. More importantly, Python 3 is the future, and when folks use Python 2 impacts how quickly they can stop supporting two major versions.
If you use Python 2.x, expect everyone else to migrate to 3.x before you, and then the Python folks to drop support of 2.x, and then a major security issue happens and you're the last person effected by it. For a 7DRL you might not care about this. If you're trying to make a new major Roguelike, however, this could definitely be an issue.
Unfortunately, on Windows having Python 3 installed interferes with basically any other program that has features to use Python. (LibreOffice/OpenOffice fails to start if I have it include Python support, etc.)
Last time I looked at Python Roguelike development my requirement to use Python 3 meant I was writing my own UI code using TkInter. This was ~3 years ago, though.
My advice: Look in to py2exe (for Windows) and py2app (for Mac OS X). They'll allow you to make a first-class application using Python. Both py2exe and py2app work basically the same way, they create a ZIP file of the compiled Python code bundled with the Python interpreter.
To finish it off, on Windows you need to use a installer-creation program like the Nullsoft Installer. And on Mac OS X you'd create a "DMG" file. If you have access to Windows and Mac OS systems it is straight-forward to create packages for Windows, Mac OS X and DEB-based Linux distributions. (I've never created packages for other Linux package management systems so I can't say how easy it is.) At a university it should be possible to get access to both Mac OS X and Windows machines. Otherwise it's probably easiest to have a Mac and either dual-boot or have Windows in a VM. (Linux runs smoothly in a VM everywhere without license issues.)
By shipping your game as a standard installer for Windows and Mac OS X and source for everything else, you're basically completely covered in terms of making it easy for the folks that "need" it easy, and making it possible for the people using odd operating systems you've never heard of.
Cheers,
Steven Black