I was again amazed on what I saw in Assembly Summer 2014 1k intro competition. In this competition the programmers make a program what has maximum size of 1 kilobyte. And they do amazing thing with those tiny programs: 3D graphics and audio are included. It is really hard, because typically a simple “hello world” program compiled with any normal compiler created very much bigger executable file! Wed technologies are also available, but still it is very hard to fit much to 1 kilobytes, when typical web pages without much amazing are much much bigger. I know how hard it is because I have years ago tried to make amazing 4k intros, and it was really hard. Making 1k intro is much harder, but nowadays they look much better than 4k was some years ago.
Some links to 1k intro making related material that could be useful: