You know those late Worms games where you have an optional rule randomizer slot machine ?
Sideboards are expanded to 30 cards, but you can't make more than 15 swaps. (You'll need every single one of them.)
Spin the wheels before sideboarding.

Wheel One: Gamechanging Rule

Slot 1.1: Heavily Wounded
Damage never wears off.

Slot 1.2: Bear Forest
All creatures have base power and toughness 2/2.

Slot 1.3: Slowride
Spells cost more. All lands enter the battlefield tapped.

Slot 1.4: Fast&Furious
Spells cost less. Whenever a land enters the battlefield tapped, untap it.

Slot 1.5: Valar Morghulis
Nonland permanents have Vanishing 4.

Slot 1.6: Shandalar's Bane
During each player's upkeep that player exchanges control of random target artifact, creature or land he or she controls, for control of random target permanent of the same type that a random opponent controls.

Slot 1.7: Paranoia
All creatures without Morph have Morph, and their Morph cost is equal to their mana cost minus

Slot 1.8: Oh No
All instant and sorcery spells have storm.

Slot 1.9: Dead of Summer
All players skip their draw steps, but have "pay 1 life: draw a card".

Slot 1.10: Shaherezad
All games start with a subgame.
When that subgame ends, all cards are shuffled back to their owners' libraries, and the real game starts, but the player who lost his game starts with half of starting life total, rounded up.

Slot 1.11: Crapwalking
Before first game, players sideboard, then set their sideboards aside, then exchange decks until the end of the match.

Slot 1.12 Multiple and Simultaneous
Players take steps in turn order. (Player 1 untap, Player 2 untap, ... , Player X untap, Player 1 upkeep,...)

Slot 1.13 Triskadekaphobia
If a player's life total is equal to 13, that player loses the game.

Slot 1.14 Cabal Pit Fight
Players can't control more than one nontoken creature.

Slot 1.15 From UC With Love
All Mythic Rare cards are Darksteel Relics.

Slot 1.16 Mirrored Biochemistry
Creatures have switched power and toughness.

Slot 1.17 Azorius Are In Charge
If a nontoken permanent would enter the battlefield from anywhere but his owner's hand, exile it instead. If a copy would resolve, exile it instead. If a card would be put into a graveyard from anywhere, exile it instead. If something would copy anything, exile it instead. If a spell or ability would be played outside of it's owner's main phase, exile it instead. Players can't take additional turns, or control other player's turns. Nothing can be doubled, tripled, quadrupled, or squared. Players can't cast spells without paying their mana costs or for . Permanents can't change their controller. Cards can't leave exile. Yes, this includes blinking.

Slot 1.18 Telepath Fight
Players play with their hands revealed.

Slot 1.19 Suicide Squad
Whenever a creature deals damage to a player double that damage, then it's controller sacrifices it, then draws 2 cards.

Slot 1.20 There Can Be Only One
Whenever a creature dies, put two +1/+1 counters on each creature that dealt damage to it this turn.

Wheel Two: Starting Conditions


Slot 2.1: Why Don't We Just Die
Starting life totals are 50% larger, rounded up.

Slot 2.2: Who Said Life Must Be Fair
Starting life totals are a random number between 5 and a normal starting life total, different for each player.

Slot 2.3: Okay So Four Is A Number Of Death
Starting and default maximum hand sizes are 4.

Slot 2.4: Okay So Ten Symbolizes Completion
Starting and default maximum hand sizes are 10.

Slot 2.5: Okay So Seven Is Associated With Wisdom And Mystery
Instead of drawing starting hands, players search their libraries for them.

Slot 2.6: Stacked Fight
After choosing their starting hand, each player rearranges his deck.

Slot 2.7: We Fight Each Other As God Intended
No sideboarding.

Slot 2.8: Brink Of Madness
Deck sizes are halved.

Slot 2.9: Generals
Each player may pick a creture from either maindeck or sideboard as their Commander. (It doesn't have to be Legendary.)

Slot 2.10: Three In The Morning
Starting hand sizes are 3, starting life totals are 13.

Slot 2.11: All Your Colors Combined
When drawing a starting hand or mulliganing, player may draw X less cards to search their library for X basic lands with different colors, revealc them, put them into their hand, then shuffle their library.

Slot 2.12 Kaladesh Feltival
Players start with four Ornithopters.

Slot 2.13 Transformer War
Each player may choose to start with:
Two 1/1 Flying Thopters
Three 1/1 Servos
One 3/3 Golem

Slot 2.14 Let's Do It Quick
At the first turn of the game, players may play any number of lands.

Slot 2.15 Secret Weapon
Players add to their starting hand one card from the following list. (the player who goes first picks last etc) :
Fumigate
Glorious Anthem
Mind Spring
Clone
Fallen Angel
Inquisition of Kozilek
Char
Flameblast Dragon
Sylvan Caryatid
Terastodon

Slot 2.16 Vintage Taste
Starting hand of each player consists of proxies of the following cards:
Black Lotus
Mox Pearl
Mox Sapphire
Mox Jet
Mox Ruby
Mox Emerald
Library of Alexandria

Slot 2.17 Funfactfiction
Instead of drawing starting hands and mulliganning, players Fact of Fiction each other for 15.

Slot 2.18 All Hail The King
Whenever a source a player controls deals damage to his opponent for the first time, he becomes the Monarch.

Slot 2.19 That Was The Plan To Give You A B...r
At their first upkeep, each player may Scry 7.

Slot 2.20 It's An Omen, You Just Runned Out Of Automation
At their first upkeep, each player may Fateseal 7.

Reserved for wheel 3

Random thoughts

Thinking With Portal: Creatures have no subtypes. Instants are sorceries. Enchantments are sorceries that last "Until end of turn". Artifacts and nonbasic lands are Wastes. Cards from "Portal", "Portal Second Age" and "Portal Three Kingdoms" are unaltered.

Speed of Light: All nonland cards have flash. If a card already had flash or was an instant, it has Split Second.

Sinking Ship: At the beginning of each player's upkeep, if that player controls four or more permanents, he or she returns a permanent he or she controls to its owner's hand. (Alternate: For each four permanents a player controls, that player returns a permanent he or she controls to its owner's hand)

Bump

Something I noticed this time, Vintage Taste is going to ruin any player who doesn't go first: Drop all moxen and the Lotus. Tap Sapphire+1 to Time Walk. Crack lotus for blue, Ancestral, play what you can of what you get: you have and one of each of any three nonblue mana but you need to hold back, because when you've played out everything you can you Timetwister. Everybody else's P9 goes away. If it weren't for the Timetwister it wouldn't be so insane...

A Thought (thanks Microprose!)

Shandalar's Bane: Power Struggle is in effect for all players.

Oh, snap !
Plan B: Moxen, Lotus, and Library, for a total of 7 cards.

Also, I accept your new suggestion ! Now, it's on 7-th slot.