well, puppy does have the look of a retro distro of Linux, that comes from the creator's choice of programs and the look he chose. 

 but while it does have a somewhat retro feel to it, it uses quite up to date software, such as the Linux 2.6.25 kernel, gtk 2, 2.7 rox (i think that's what 4.1 came with), and basic hotplugging support.

for a somewhat more retro experience, using 3.01 with a retro kernel might be a good choice. possibly theming it with a retro icon set might be a fitting choice. and possibly might make a good puplet idea if you add some older software to it.

Since I imagine that you might be somewhat new with the Puppy community, I feel it would good to say, Welcome to the kennels. And i hope you enjoy your experience with Puppy.

- J-Bob