I think it's important to note that when they did this game 20 years ago, you had a similar "build vertically with basic parts, and you can install a variety of props in your layout that aren't brick-built in-engine"
You could build a stack of parts that moves with a hinge, and program start position, range, and speed. You could put a steering wheel on a pile of parts and it became a land vehicle. You could put a joystick on a pile of parts and it became an air vehicle.
LEGO Worlds, I looked up LEGO Creator to verify my memories, and I found these for goodness sake!
Then 5 years ago in Lego Universe, you could get all into the special parts and SNOT and send your models into the servers to bake into custom props.
I wish when the lego worlds engine was developed, they'd made an allowance for, obviously something with a complexity cap, but something like these features.
Maybe a plugin in Lego Worlds that could receive custom props from an additional "Lego Worlds Kiln" software suite. You'd get a build tool like in lego universe. You'd have a blank figure to claim a seat for an "enter vehicle" interaction. You could place a little "operating range" shadow and map hinge reactions to a button that prompts when you're there (like a mailbox or door that pops open when you stand in front of it and press "A", or an elevator that lifts when you step on).
You could select a part or group of parts and label it "climbable surface". You could take some tiles and label them "slippery". You could have a little "spark" that you stick on a connection you want to operate as a hinge, axle, or slider. You could imbue a part or group of parts with a "hazard" marker to show what's a sword edge, the face of a hammer, a buzzsaw. Is it fire or just seaweed? You could, like the hinge spark, give a spot where it splits. label parts around that to trigger the split. maybe that's the weakness on your mech's sword arm, or a way to detach a life boat.
You could select a place on your model that launches a projectile, and the speed of the launch. The projectile could be a model that has any of the bells and whistles itself.
You could imbue parts with a particle effect so that projectile has a fire out the back, that buzzsaw makes sparks, that snorkel makes bubbles, that chimney smokes. That puppy drools waterfalls.
Does a model sink or float? does it break? With fists or does it take an explosive?
Does it operate on it's own? how does it move when it's relaxing? what makes it react if it's not?
You could have a model that's a snake with hinges in the middle, minds it's own business chasing it's tail. if you step into an "operating range" in front of it's face, it triggers a lunge animation with a jaw hinge. all the parts around the jaw are labeled a hazard so you take damage, but maybe you can snap off the teeth with a punch. maybe you can grab the tongue and that triggers a reaction where it slithers off whimpering.
You could make a factory with a smoking chimney that has a big button. that button is a blinking light. there's a prompt to touch it and it drops a slow projectile which falls onto a "slippery" track and falls into a pile off the end of that. you named it "enormous chocolate chip cookie".
Then you could make a truck, that drives like a truck. At the push of a button it transforms to a new operating mode, where legs unfold and a cannon sprouts out of the top. that cannon fires a ball which lands and splits into little greedy brick built goblins, with a seeker behavior. These goblins go straight for an object called "enormous chocolate chip cookie". these goblins are immune to damage that isn't from something called "goblin whacker"
Back in the factory there's a wall with a ladder behind it. standing in front of the wall triggers a "read the sign" "in case of emergency, break glass". the wall is labeled breakable, the ladder is labeled climbable. theres a turret with a minifigure seat at the top - guess what the turret shoots.
When you've given your model the behaviors you want, you bake it in the program and it becomes a prop, a building, a vehicle, a creature, a robot, a drawbridge. doesn't really matter. But it locks into one piece. or 10 pieces connected on some hinges, but the 10 pieces were each baked together out of 45 lego pieces which now behave manageably, and do something that becomes a simple thing always works the same, from a few simple options that made anything possible - and then you can port it in for play however you just set it up.
And that is what Lego Worlds is missing.