Demos came about as a sort of “visual graffiti” that preceded video games that had been cracked (had their DRM removed) by a team or person who wanted to visually show off their artistic side as well as their technical prowess. In the early days, computing capabilities and space were severely limited and that required a certain finesse to create something amazing using very limited means. That meant that the music and animations created in this format required creativity as well as algorithmic magic, and physical parties sprung up way before the internet as a way to share files and knowledge and to compete and inspire each other. Demoscene: The Art of the Algorithm is a well-crafted documentary that narrates the history of the demoscene and demoparties, and captures the essence of the modern-day scene.
Nectarine is a demoscene portal that’s still updated with demos
Pixeljoint Pixel Art Resources
Keygenmuysic.net Download .mod files ripped from demos or keygens / cracks. Requires a .mod player like one of the apps on Modplug.com
Keygen Music Jukebox Listen to demoscene / keygen music without need for a .mod player
Trackers are the original old school way to compose music on computers, using hexadecimal to assign effects and notes. Impulse Tracker was the one I used on DOS, but there are modern day equivalents like Sunvox and Psycle.