Not sure if this is what you were thinking about, but .kkrieger was 96 kB and looked very impressive when it was released: https://www.pouet.net/prod.php?which=12036
replywell there have been micro attempts over the years
replylike this is 512 bytes (half a K)
https://www.pouet.net/prod.php?which=83795
but the one I am thinking about had textured walls and sound
it used some insane levels of packing and exploits to render