People play different games, for different reasons.
Magic's success as a game stems from, among other things, its balance of opportunities: fictional, creative, competitive, logical, etc. That balance ebbs and flows, and Planechase represented the firstMagic product from Wizards in some time to target primarily social players. It's primarily social because it increases the random element in Magic games. That variety enriches the play experience, but some players prefer more opportunities to manipulate the outcome in their games. That means more planning and less chance.
Of course that's a generalization but, to the extent it's true, Planechase is a useful tool. When played with the prescribed ten-plane decks, Planechase achieves a good balance of randomness ... a spicy mix of circumstance, changing the situation in semi-predictable ways as the game progresses. That changing environment makes things dynamic and dramatic, and can even be a good challenge to the players' adaptability.
Unfortunately, individual plane decks require extra preparation on the part of every player. The most common alternative is to play with a "communal" planar deck of every plane, shuffled together in the middle of the table. While easier to manage, this increases the randomness by an order of magnitude and turns off many players who like a modicum of predictability in their games. The planes are individually balanced, but they're still quite potent. With no knowledge or control of what's next, the communal plane deck can be frustrating to navigate. Many plans won't survive a planeswalk so it's not worth investing in any plan (plane?) more than a turn in advance. Even worse, running from an untenable situation (at an unknown, significant expenditure of mana) can result in a jump straight out of the proverbial frying pan.
Enter ... The Eternities Map.
By giving players some control and information about what happens next, the hope is to rebalance the chaotic Planechase elements with the plans which breed interesting games. Doing so in a flavourful way protects the immersive experience.
The basic concept of the Eternities Map is the addition of a spatial relationship between planes. Playtesting shored up the rules for the most interesting, flavourful experience.
Before taking mulligans, shuffle one of each plane into a deck and deal out five as below. Place a counter on the middle plane, which is where the game will start.
The initial setup during mulligans. This game will start on the Eloren Wilds; an important piece of information.
Once the game has started, turn the surrounding four cards face up.
The first five planes, representing the movement options available after mulligans are taken.
Whenever a player rolls the Planeswalker symbol on the die, instead of moving to a random plane the game normally (see Rule #5) moves in one of the four cardinal directions. The active player chooses the direction after the die is rolled.
Whenever the game moves to a new plane, first collect and shuffle into the deck any planes more than 3 steps away from the new location. Leave the rest in place and deal out planes into any blanks around the new plane.
The pink line describes the path taken by the first three planewalks in a game. The red crosses are the planes (more than three steps away) shuffled in before dealing out those around the new planes after the third move.
In addition to moving in one of the four cardinal directions, a player can "Hellride" in a diagonal direction if (and only if) the plane in that direction is still unknown. If a diagonal neighbor plane is face up, Hellriding there is not a legal move.
Hellriding represents a sacrifice of safety and control for speed, in effect running "anywhere away from here." It's usually used to put extra distance between oneself and a particularly undesired plane.
Counters remain on planes (such as Naar Isle) until they are removed from the map by moving more than three steps away.
By starting with only a single plane face up, Mulligan decisions are informed. Then important information becomes available and the scheming starts as soon as the rubber hits the road.
Rule #4 is purely practical, to keep the table space requirements under control. If you've got a huge spare table nearby, the planes can be left in an ever-expanding map. By shuffling the now-distant planes in before dealing out new ones, the blind eternities gain an appropriately non-Euclidian geometry.
Rule #5 was introduced because we found the ability to go back to the same plane can be frustrating. Some planes in particular are asymmetric regarding entry/exit; for example the first person to untap onLethe Lake gets milled for ten and will always be behind in the race unless they can get away. A prohibition on backtracking resulted in each step requiring three successful rolls to reverse, which was too disruptive to normal planning. The introduction of riding hell-bent to as yet unknown planes resulted in an optimal head start of one plane when escaping, but at a cost.
The Eternities Map variant of Planechase balances out the random factor while still mixing things up, and without requiring the preconstruction of plane decks. It allows for an improved degree of plan and counter-plan, which certain players are more likely to enjoy, while still providing interesting stories.