This is a very good freeware and open-source ray tracer. Most of the 3D graphics in our games are developed with this. You will like it if you like to code.
This is the main application I use when making music and sound. It is a very advanced software synthesizer studio and its usage is almost endless. It is unfortunately not freeware.
Most of our software is programmed using Delphi 6 (or higher in the future). It is a object oriented Pascal language. It is probably not the best out there, but I'm used to it and like it. This is not freeware either.
Here is a selection of the oldest and best Commodore 64 games and you can play them online in a Java applet - this means directly in your browser. If you look down to the right on the page you can choose to play Stix, this is the C64 version of the old Styx.