Also hard to reproduce: the selection of objects, the art style (decidedly Japanese) the ambiance (king/prince/planets, the pool table when you lose), music and sounds, and a lot of the little things that make it delightful like things running away, the selection of items - the fact that parts of the world that are not objects become items to pick up at large scales.

It's the chaos, the music, the growth over a level, the characters, the visual design, the sound effects.

The sequels showed that when any one of them suffers then it makes for a less endearing game on the whole.

Also, the items in the game are very artfully arranged.

This version (the part I played) just dumps everything on the floor and the music is lifeless.

The other two are:

1. The whimsically melancholic music 2. King of All Cosmos' majestic facial hair and crotch bulge

You start off small picking up crumbs and trinkets.

You get larger and pick up sports equipment.

Then you start picking up people and they run away from you.

Then cars. Then buildings. Then cargo ships.

Then mountains. Weather systems.

Planets.

And the level designs are fun and intricate. The levels you're inside eventually become the objects you roll up.

You start inside a house at the size of a mouse. Then later you come and roll up that house and its whole neighborhood.

It feels like the horror movie "The Blob", except it's quirky and adorable when you start devouring the whole town.

All of these clones are flat and miss the incredibly good level design.

Later, I bought Katamari Damacy, and it doesn't have that aspect. You can't suck up everything on the planet. You can get moderately bigger and pick up objects the size of a car instead of objects the size of a paper clip.

What you're describing just isn't a strength of the original game; it was a strength of the sequels.