In 1997, size-optimized graphics-mode programming seemed like a nice and rewarding thing to do, so I decided to attend the PC 4-kilobyte intro compo at that year's Assembly party. My entry was called Helium, and it eventually ended up first in the competition. It was also my first demoparty victory ever.
Helium was an MS-DOS-based 4K intro built around a simple (and silly) scifistic storyline including 3D spaceships, a texture-mapped wormhole and even a space battle scene. There was also a musical soundtrack, but it wasn't played during the competition - in fact, the rules explicitly forbade the use of any sound in the competing version. It was still rather unusual in 1997 to have any consistent narrative or sound in a 4K intro.
The full version (including the 300-byte music player) was well under 4 kilobytes (3756 bytes, to be exact). I could have used the unused space for some additional effects or a longer storyline, but the demo seemed finished enough even without filling up the size limit.
During the following years, I wrote some more sub-4K intros which weren't nearly as succesful. I had some enthusiastic and groundbreaking technical ideas (such as animated 3D robots, speech synthesizers and size-optimized vector graphics images) but I always ran out of time with them and only released somewhat average material.
I haven't released any tiny intros for many years now, but there are still some ideas I'd like to try out some day: