waiting for your retro game to be announced here.. ;=)

About the problem you are facing i must first admit i know nothing about mac nor retina stuff, but I'd verify the following:

• the font test of the tk installation looks the same? all fonts ugly? If you have Mastering Perl Tk in the chapter 3.4. Using Fonts Dynamically there is an useful program to choose fonts. Try it to see/confirm all fonts are pixellated.
• the program runs fine on other osses?
• if the problem seems to be in the conjuction of Tk and your OS you can read carefully this bug report that seems very close to your. This lead to this page where some solution seems to lay, but where users also complains about lost display..

L*