A stream by Casey Muratori showing an internal debugging/program exploration tool he made. The whole thing is long (and worth watching if you're interested), but if you watch for a couple of minutes from the time linked (49:13) you'll get a decent idea of what he's doing:

Thanks for the link. Do you know what tool they use for this?

Do you mean how he made it? I'm pretty sure it's just written in C-style C++ using some of the windows APIs for drawing and client/server sockets. I'm not sure if that's what you're getting at..?

I more meant if you happen to have a link to the debugger itself.

Oh I see, sorry. Unfortunately not, it was internal to one of the companies he worked at. I know some people are hoping he'll release the source at some point, but I'm not sure if he owns the IP for it...