[ck2]

the Wolfenstein3D-like game in only a few hundred bytes WITH SOUND might be even more impressive even though it's like exploits all the way down

oddly can't find a link to it at the moment

[M4v3R]

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

[ck2]

well there have been micro attempts over the years

like 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