Why is Katamari Damacy the best collect-a-thon?
Because it introduces interesting choices into the process of collection, and makes it arcadey and non-persistent. Instead of slowly building up tons of tiny chits you need to manditorily scrounge across the level, you’re given a massive number of objects and allowed to take whichever ones you want, progression will not be barred by not collecting everything. Katamari fundamentally changes the game from visiting every single node to attempting to weigh the value of each node and the nodes around it. Katamari is the traveling salesman problem on steroids.
Collectathons are typically subsidiaries of adventure games. They usually have a large number of collectables that are placed all over levels, that when collected get added to a persistent count of how many collectables you have. These are then later traded for access to areas, different collectables, or character abilities (which may grant access to new areas). These collectibles are positioned to basically lead you by the nose through every part of the level.
Katamari is not really related to collectathons at all, it’s more closely related to those flash games where you eat things smaller than you and avoid things bigger than you. There isn’t a definitive name for this genre, because there aren’t really many games in it. One suggested name is eat and grow. Katamari is fundamentally about evaluating, “am I bigger than this thing?” and, “how many things smaller than me can I currently absorb?”
Usually eat and grow games focus exclusively on the “Am I bigger than this thing?” part. Growth is relative to how big of an object you’re eating, so you want to eat the biggest thing that isn’t so big you die, or eat a ton of smaller things to make up in volume. In Katamari, you don’t die if you hit an object larger than yourself, though you might lose some objects from your ball. Katamari is less life or death than other eat and grow games in this way, but it makes up for it by adding a timer. You’re given a specific size goal to shoot for, and you have a limited time to do it. This means that the whole game is about opportunity cost. You need to constantly be absorbing objects smaller than you, and moving to areas with progressively bigger objects to succeed in Katamari. By adding the timer, they make the objects you absorb count. You can’t take your time absorbing everything, you need to prioritize.
On top of that, katamari has some wacky controls. You use both analog sticks to roll the ball, to rotate it, to dash. You can slowly climb up walls of a certain scale relative to you. They also include live objects that may chase you, move independently, or run away. And building the katamari lopsided will have it roll lopsided. These all add additional considerations on top of the core idea. Plus themed levels.
It will never be as appropriate to link a speedrun ever again. This is how the game was literally meant to be played (except of course for quitting out of the levels when you get a big enough ball).