Homeowners’ Associations. There’s room for only one arbitrary tyranny on my island.
The one-handed double-middle-finger.
You will pay! Autolycus, you will pay!
Private vehicles on the highway system. Parking in the commerce districts. I will have a public transportation system that is serious about being a public transportation system.
And plenty of park-and-rides.
btw, no capital punishment in kaylasdadia. If you are a danger to society/your fellow denizens, you will be locked away where you cannot harm anyone. If you are merely a huge pain in the ass, you will be exiled.
To AK84-land. 
In no particular order
-
Mexican food
-
Burgers
-
Rum
-
Times New Roman font
What’s the point of being the ultimate ruler if you can’t be arbitrary and capricious? Handshakes are required when men and women meet.
Child abuse. It would be the only offense for which the death penalty was allowed. Death by Iron Maiden.
Ceremonial Deism.
Waivers for vaccines. Everybody gets their shots. Fuck all y’all anti-vaxxers - y’all get double.
Homeschooling (but I’d make sure to adequately train teachers and fund the school systems).
Creationism being considered for inclusion in school curricula.
Screwing around with cheesecake. In Kolgatopia, cheesecake is as it was intended - pure and unadulterated. Black market importation of raspberry-mocha-truffle-infused-with-unicorn-tears cheesecake crap gets you exiled for the first offense.
ooo how fun.
I want the island to be big enough to support a population large and diverse enough to be able to self continue without immigration if needed. I vaguely remember somewhere that a starting population of 50,000 people [technically 25,000 couples that are able to pop out kids] so I would adjust it up by 20,000 to allow for homosexuals that can’t pop out their own kids.
I would make the capital city Aruville Bucky Fuller’s Old Mans River City project, just updated a bit. That would give me the option of keeping the individual residences the same design era smaller residence sizes, or updating to a larger current desirable size. I would definitely update to cable optics and more electrical outlets, modern communications and entertainment options. Not sure I would really want the football and baseball arenas to be internal, I think just parkland and a swimming area/water park in the middle might be funner. I would also make sure that it was fully supported by mass transportation internal, not private vehicles.
On the rest of the island would be the equivalent of the huge corporate farms in the middle of the US that produces various foods for the populace, and for selling for international currency. On a pleasing beach area would be set up a tourist area that is designed like a Sandals sort of resort, and an area nearby that is designed for the cruise ship trade. I am thinking that we can also function as an offshore banking and records storage area as well.
There would be mass transit that circles the island hitting all the agricultural and tourist areas so there would really not be much of a need for private vehicles, though there would be a small fleet of helicopters and 4 wheelie thingies for transport off the beaten path for emergencies and whatnot. I think a small number of imperially owned loaner sailboats, sailboards, 4 wheelers and other rec vehicles for leisure time activities would be worked in there.
There would be imperially owned cable TV/radio piped into the homes along the lines of the original BBC, but also an option to purchase feed from whatever satellite companies we get in that area.
No tax free ride for any organized religion. You want a church, hold it in your home or rent a facility. Westover maniacs are allowed to visit, but the first protest they try to do, they will be spending quality time in jail. Religious repression, manias, protests and assholery is not allowed. Disturbing the peace is not allowed. If you have a problem with something, petitions are allowed. If you do not like the result of your petition, you are cordially invited to leave my imperial island.
Pretty much any form of marriage that is consensual and adult is allowed - monogamy, polygamy, heinlein style line marriages, jumping a broom. All marriages are a matter of legally registered contracts. Religion is forbidden to be a part of it. If you want a catholic priest to preside, after you go to the imperial palace and register the contract, I don’t care if you jump a broom, kill a chicken or see a priest.
Age of consent is 18. Under that, hands off unless you are the same age [obviously if there is a couple months between you and one is a month over 18 and one is a month or 2 under 18 not a big deal … keep to your own age year and you will be fine. School will be mandatory all year around, with 1 week of vacation roughly every month and a half or 2 months, hitting all sort of major hollidays. Homeschooling is forbidden, and the aim is to end up at the age of 18 with the equivalent of a bachelors degree or the technical training equivalent if you are less than bookish.
At 18 you will go to work or you can petition for a scholarship to continue on to a masters off the island. If you do not want to work, you are cordially invited to leave my island. Everybody gets universal health care, and mothers get 1 year of maternity leave. If you get married, one person works [flip a coin, I dont care =)] or both can work if they like. I would love a return to the old style of family where one person works and the other raises the kids.
As it is essentially a company town setup, you work a straight 40 hour week, with 30 days vacation per year, and 14 days sick time. It is all universally paid at the equivalent of minimum wage because housing and base utilities is included in your universal citizenship. Everybody over 18 is required to vote, serve on juries and on my equivalent of the senate as randomly chosen my lot. Not sure what to do about military but I am sort of leaning towards universal service, israeli style.
Name changes (for business).
Think wisely before you name your company or product, because once it’s established you cannot change the name of a company or product. You’re Hewlett-Packard, none of this HP stuff.
By the same token if you buy out a company, but you only own the products. Under my regime, Compaq no longer exists. Hewlett-Packard (not HP) can sell Presarios, but they are Hewlett-Packard Presarios.
If the general public refers to your company by initials or a cutesy nickname, that’s o.k., but you don’t own the nickname and you’re not allowed to use it for marketing, nor prohibit others from using the nickname. You also don’t own the first two letters of your company name. You don’t want a competitor selling McBurger’s? Come up with a new product and name it McBurger before anyone else does. (And no, you can’t just start calling your regular hamburger the McBurger. That violates the renaming law.)
Religion
The OP asked for one thing to be banned.
I would ban people who can’t follow directions. 
CAFOs(AKA factory farms) and imports of all meat grown there, even though I am very much a carnivore.
Endnotes. If you want to cite something or make an extraneous comment, use a footnote. Why endnotes aren’t already banned is beyond me.
In the Polygnostic Tyranny of Sunspacia, loud vehicles will be banned. This includes vehicles with fart-can mufflers, loud pipes on bikes, those ridiculous whistle tips, and monster sound systems that can be heard outside the vehicle. Anyone found to have deliberately modified their vehicle to be louder than stock will be composted without mercy.
Vehicles that need to be loud for their operation, and for which no quieter substitutes are available, will be granted conditional operating permits. The moment a quieter alternative is available, the loud vehicle’s operating permit will be revoked.
Over-the-top fundamentalist religion.
Any law interferring with behavior that does not endanger life, property, or the environment.
Man, I missed an opportunity. I should’ve said Phred Phelps. 
Ramen noodles. That shit is just nasty.
Clippy the Microsoft Annoying Paperclip. Little bastard shows his face in Marli-land I’m gonna tie him between two horses and straighten his ass out.
Sparkly vampires, or anyone who’s okay with vampires who sparkle, or anyone who wears glitter (so they sparkle) and they’re not at a rave, or any woman over the age of 30 who thinks it’s appropriate to lust after angsty emo teenagers with floppy hair. Who sparkle.
Alarm clocks. They piss me off.
Most names that end in “R”: Trevor, Cooper, Hunter, Fisher, etc. Terrible, terrible names that make you sound like a medieval journeyman.
And really, is naming a child Trevor somehow dooming him to automatically become a douchebag? Maybe any parents who think that is a good name are the type that would inevitably raise a pretentious twat.
Inspired by sitting down to watch a show recorded a few nights ago:
Delaying or preempting a scheduled broadcast for any reason without at least 48 hours advance notice. This means if you are televising a live event of any kind you schedule for as much time as it could take, not just as much time as you think it should take.
It also means no more “We interrupt this program for a special news bulletin.” News only merits an interruption if both of the following criteria are met:
- There is immediate danger to the entire viewing area.
- The danger can be averted if and only if the entire area is informed.
The assassination of a public figure, even the Ultimate Ruler of My Country, does not merit an interruption. I’ll still be just as dead when the 10:00 (or 11:00 depending on your time zone) news comes on, and people knowing about it sooner won’t bring me back.
I don’t either. They’re a wondorious god-send that increases your movement speed.