what are the parameters of t1? are they negative?

[jpmeyer]

Off the top of my head, here are some:

1) Your deck must operate so that you are doing something very major or turn 1/2 or you are able to respond back with Wasteland or Force of Will
2) You must be able to deal with repeated attacks on nonbasic lands
3) You cannot play spells that cost more than 3 mana unless they are artifacts

There are others, but the main question is if these are good or bad for the format.  The more that I think about it, the more that many of these simply cannot be avoided.

#1 cannot be avoided simply because of the fact that a large amount of artifact mana acceleration exists, and thus it is reasonable to assume that you will be able to have access to more than one mana on turn 1.

#2 cannot be avoided because there a large number of cards that generate these effects.  Even without Crucible of Worlds, for instance there is still Blood Moon, Back to Basics, Dwarven Miner, Price of Progress, and probably a few more that I'm forgetting that might be playable.

#3 is the case whenever efficient answers of any kind are available.  In Onslaught Block Constructed for example, there were no cheap counters available (hard or soft), which made it look like expensive spells were playable, yet it soon became apparent that even the crappy, expensive counters like Discombobulate, Complicate, and Decree of Silence were still efficient because they costed less mana than cards like Akroma or Rorix.

I want to focus on getting as close to the root as possible in order to figure out if in a lot of potential cases, restrictions would be failing to address underlying concerns.  For instance, Trinisphere is a problem, not because of the effect itself, but because enough acceleration exists so that it can be cast on turn 1, and because the nature of the acceleration makes it so that only one deck can jump-start itself.

[Matt]

3) You cannot play spells that cost more than 3 mana unless they are artifacts

I would amend this to say "artifacts or combo cards" or "artifacts or they win the game" (aka Bargain, Desire).

[Mon, Goblin Chief]

1) Your deck must operate so that you are doing something very major or turn 1/2 or you are able to respond back with Wasteland or Force of Will

Duress is another important response, while Wasteland is a respone mainly vs Trinisphere. Aside from that, agreed.

2) You must be able to deal with repeated attacks on nonbasic lands

Wasteland alone dictates this one, true.

3) You cannot play spells that cost more than 3 mana unless they are artifacts

This should be "unless you have suffficient acceleration", for example Rector, Bargain and Desire are well playable thanks to Ritual, even though you'd need 8 Rectors to make a good deck.

So well, I agree with you pretty much on these rules being unavoidable. Other possible rules might be interesting simply for the better understanding it provides in reasoning about restrictions.

No 4) is probably: You have to be able to produce direct card-(quality)-advantage for yourself.

As broken as it sounds, look at every viable T1 Deck, even aggro is playing either Thirst, Bazaar or Brainstorm, Control is overstuffed with carddrawing and combo creates mad card-advantage with draw7s and Will, which is capitalized on during the same turn.
This is probably the reason why decks similar in playstyle to Sui and Sligh just about never do well any more, they just see to few cards.
I guess this can't be avoided either, as the game is often compressed into the first turns, so that any deck that can't find it's keycards or landdrops looses right there. This is produced by rule 1, probability is against you otherwise.

[jpmeyer]

3) You cannot play spells that cost more than 3 mana unless they are artifacts

I would amend this to say "artifacts or combo cards" or "artifacts or they win the game" (aka Bargain, Desire).

Good catch

[JACO]

3) You cannot play spells that cost more than 3 mana unless they are artifacts

I would amend this to say "artifacts or combo cards" or "artifacts or they win the game" (aka Bargain, Desire).

I would amend #3 to something like 'You can rarely play non-artifact spells that cost more than 3 mana.'

Yawgmoth's Bargain, Skeletal Scrying, Mind's Desire, Tendrils of Agony, Fact or Fiction, Arrogant Wurm, Roar of the Wurm, Akroma, Spirit of the Night, Mind Twist, Gush, Abassador Laquatas, Worldgorger Dragon, Control Magic, Diminishing Returns, Time Spiral, Academy Rector, Flametongue Kavu, Siege-Gang Commander, and plenty of thers fit into this category.

[jpmeyer]

How many of those actually cost more than 3, though?  Bargain, Siege-Gang, Akorma, Gush, etc. aren't getting cast for more than 3, and like Matt said, most of the ones you listed that are more than 3 will probably win you the game, like Mind Twist.

[Azhrei]

Minimize interaction with your opponent or interact with them in such a way as to remove them from relevancy to the game's outcome.

[Machinus]

1) Your deck must operate so that you are doing something very major or turn 1/2 or you are able to respond back with Wasteland or Force of Will
2) You must be able to deal with repeated attacks on nonbasic lands
3) You cannot play spells that cost more than 3 mana unless they are artifacts

I think these are good starting points, however I don't think that the constraints for success in Type I are so easily defined.

On your first point, the early game is easily the most important part of Type I, since this may be where the entire game occurs. In weaker formats, the way that the game breaks down here is that you must play a threat, put up a defense, or generate tempo, which could include both of those. The first turn or two of a Type I game will contain establishment of resources, and an attempt to deploy the deck strategy. Judging purely by the decks which are successful, you must have some way of preventing your opponent from resolving their spells. Examples include Trinisphere, Mana Drain, Duress, Wasteland, or just plain ending the game by comboing out. If you can achieve the goal of disrupting your opponent's game - if your opponent cannot win - then you will probably win. This is basically the fundamental strategy behind the good decks. The fact that this is so difficult to quantify also makes understanding of this really difficult. Having some way of sabotaging your opponent's strategy is almost a necessity, and this must be done early or you may never get a chance to do it.

On your second point, I will say that this is the converse of the first point. Your deck must be able to deal with disruption from your opponent. The answer to Trinisphere could be a FoW, to Duress could be a Brainstorm, or to Wasteland could be a fetch or basic land. You have to have ways to protect your hand, your board, and your life total. Since disruption comes in many forms, defense then is a first priority when making deck selection choices. Brainstorm doesn't net you any cards, but it provides cheap instant searching, and combines extremely well with another defense card, Polluted Delta. These two cards alone provide marginal benefits (color fixing, land thinning, mild draw), but together they form a strong defense against hand and land disruption, as well as providing a way to find the right answers.

In Type I, one of the things that is least important to defend is the life total. Decks just aren't constructed this way anymore. Win conditions are not the first priority. Sometimes they can have a significant effect on the construction of a deck (Germbus, Doomsday) but they are not played because they are necessarily good at winning. They are played because they have good synergy with a high quality disruption and defense core. This makes them "good" in Type I. This is why sligh and suicide can't compete - because they are playing the wrong game. If you attack the life total instead of the hand and board, your opponent will decimate you before you get a chance to kill them.

The third point really fits into the first two. Spells that cost three or less usually can be played during this time in the early game, because of the great acceleration which exists. Blue just happens to be the color with the strongest abilities for the game that Type I decks play, and so of course blue decks will be more prone to succeed at it.

[Smmenen]

I think the parameter that I coined over a year ago: you can't play nonblue, non-artifact spells that you cast that cost more than 3 unless it is Bargain is no longer true.  I think this view is unnecessarily narrow, even if it is empirically true.  

However, the parameter I stated in another thread: you must have either Wasteland and FOW or a play that could lead to winning the game on turn 1 is the defining parameter of the format.  This parameter isn't as bad as it sounds.  A turn one Wild Mongrel satisfies this requirement, imo.  

I also agree that decks must have some resliency to repeated non basics attack either through speed or immunity (basic lands).

[Matt]

How many of those actually cost more than 3, though?  Bargain, Siege-Gang, Akorma, Gush, etc. aren't getting cast for more than 3, and like Matt said, most of the ones you listed that are more than 3 will probably win you the game, like Mind Twist.

What if you rephrased this as:

"Don't include anything you can't play before turn 3"?

[jpmeyer]

How many of those actually cost more than 3, though?  Bargain, Siege-Gang, Akorma, Gush, etc. aren't getting cast for more than 3, and like Matt said, most of the ones you listed that are more than 3 will probably win you the game, like Mind Twist.

What if you rephrased this as:

"Don't include anything you can't play before turn 3"?

That's a good way to put it.

[Sylvester]

I think this can be refactored a bit better.

1 & 3: You must have an important ("I Win") advantage by turn 1-2.

1 & 2 (well, its converse): Or else you must turn back your opponent's clock.

"Win by turn 2 or make sure your opponent doesn't get there", or, more generally, "Be fast or make the other slow". Nothing groundbreaking really.

What's interesting is that we now have so many broken cards that card advantage usually isn't important anymore. I believe even the decks that run card drawing tend to use it as tutoring. You don't need to hold two bombs at the same time, but you must cast at least one. The short-term availability of mana (not mana development - land drops are still next to worthless is what counts now.

Of course, I'm not a good player, and I only follow the scene from afar, so take that with lots of salt.

[Bram]

most of the ones you listed that are more than 3 will probably win you the game

Isn't the whole point of 'spells that cost more than 3' to 'probably win you the game' in any format?

I'm thinking Spiritmonger / Ravenous Baloth in extended The Rock and stuff. How are they different from game-swingers like FTK in our format?

[jpmeyer]

Ravenous Baloth, Horobi, etc. are good and all but they don't win the game like say, Memory Jar wins the game.