CAPTAIN
A 1v1 Magic: the Gathering format.
Forty cards. One Captain. Twenty life.
Take a Commander deck off your shelf. Keep the commander.
Cut the 99 down to 39.
That's a Captain deck.
Nothing to buy, nothing to learn
Same singleton rule. Same color identity. Same legendary creature in charge. The cards are the ones already in the box, the rules are the ones you already know, and the deck is one you have already built once.
What changes is the shape of the game. Half the cards means every draw matters more. Half the life means a threat you ignore for a turn is a threat that kills you. One opponent means nobody is politicking, nobody is hiding behind the table, and the game in front of you is the whole game.
And if you would rather build from nothing, the cheapest tuned Comp deck we have priced comes to $37.53 for all fifty cards, with nothing on the Reserved List and nothing above nine dollars in it.
Your Captain never dies
Your Captain starts in the Captain's Seat and you cast it from there any time you could normally cast it. Whenever it would go to any zone other than the battlefield or the Seat, you may put it in the Seat instead. Dies, exiled, bounced, milled, tucked: same rule, every time.
There is no Captain damage. Twenty life is the only clock that matters, and the seat tax is the only thing that ever punishes you for using the card you built around.
Nobody mulligans, ever
Keep what you draw. Forty cards with about seventeen lands makes hands naturally keepable, and because nobody ever mulligans, nobody ever knows whether their opponent kept a good hand.
Hand quality is hidden information for the first time in Magic. Read your opponent, or don't.
Two tiers, and one of them has no rules
Casual has no deck rules at all. Mash precons together, let the first legend you pull be your Captain, proxy whatever, bring your worst. Nothing is illegal in Casual, so there is nothing to check and nothing to argue about.
Comp is the real format, and it is four rules: register fifty, three Game Changers at most across them, best of three with the sideboard, paper only and no Reserved List. Your Captain is locked at registration, so a legal fifty is checked once and never again.
Nothing is banned for power
No card is excluded from Comp for being too strong. Two kinds of cards are excluded, and neither reason is power: cards that cannot function in a registered one versus one match, and cards you cannot reasonably buy.
If the data says a card warps the format, it moves to Casual. Cards get a price, not a prohibition.
The whole format is one page.
Five minutes and you will know all of it.