<p>I'm looking for an implementation of the <a href="http://en.wikipedia.org/wiki/Logo_programming_language" rel="nofollow noreferrer">LOGO</a> programming language that supports 'dynaturtles' - animated turtles that can programmatically change shape, speed and direction as well as detect collisions with each other or other objects in the environment.</p>

<p>Back in the mists of time when the earth was new and 8 bit micros ruled supreme, <a href="http://en.wikipedia.org/wiki/Atari_LOGO" rel="nofollow noreferrer">Atari LOGO</a> did this famously well.  One could create all sorts of small games and simulated environments using this technique very easily as that implementation of the language had a very well thought out, elegant syntax.</p>

<p>I know about LCSI's <a href="http://www.microworlds.com/" rel="nofollow noreferrer">Microworlds</a> but I'm looking for something I can use to get some friends and their kids involved in programming without breaking my budget.</p>

Digging around a bit online, I've found
OpenStarLogo
. Though they don't specifically mention "dynaturtles" the docs do mention collision detection.  The site has code and documentation downloads.
From this
wikipedia article
, under the Implementations section, there is a PDF listing known current and antique implementations.  Some of these, such as
StarLogo TNG
and
Elica
have support for 3D objects.  These are definitely not like the LOGO programs I wrote as a kid...