There's a variant called Frontier Magic, which is kind of like this. Maybe you might want to do a regular magic set, but intended to be played with that (or something slightly different, like having destroyed lands take creatures with them)?

I guess it's a bit like that, but the Positions are only used with creatures - enchantments, lands, artifacts, planeswalkers and all else stay on the original battlefield.
It might be better to just make a variant where the Land are the Positions. Dunno yet. We'll see how it goes.

Pretty cool idea, but I think there's a couple of problems.

It's a big hassle to move creatures around the battlefield into compartmentalized 'positions', especially if you have equipment and auras and creature tokens. When you attack and block, you move creatures around the table, but it doesn't matter where; pointing works just as well. But with this, their actual positioning on the table matters. This also becomes problematic with attacking and blocking from different positions, and even more of a hassle when using morph.

I'd suggest that you use the plane cards template for positions; or at least, a length-wise frame instead of the regular one, so that it's easier to move them with one another.

While it does open up new design space and interesting elements, I don't know if adds enough to make all the hassle worthwhile. The point of positions is that you have more than one battlefield, which I think is really cool. But, you could probably create various battlefields with evasion; flying, shadow, landwalk - they all create restrictions on whom can block whom, which is kinda the point of moving between battlefields.

I often find that trying to reduce a mechanic like that will either show why the new mechanic is worth keeping around, or it'll give a new way of looking at something earlier. Might help.

I'm not sure the idea is worth the difficulty, but I will give you that it is one of the more interesting custom card type ideas I've heard.

I can see where Bass is coming from, but I don't think the use of evasions is reason enough to vacate this idea. I mean, afterall, there are also arguments that all card types are variations of enchantments and that a great many keywords are variations of kicker. That doesn't make artifacts, planeswalkers, entwine, or replicate bad ideas.

I do also think Bass makes an excellent point about looking at mechanics from new angles, though.

I like it. It may be a small hassle, but I don't think I would mind to much.

You could make positions like:

The Skies - Unknown Cost
Position
Only creatures with flying may enter The Skies.
Creatures in the skies get +2/+0 and have vigilance.
: Move target creature into The Skies.

I think it would be best if all Positions where Legendary, like planeswalkers.

Hmm.. I like it, as it weaves additional layers of complexity into the game, which I always enjoy.

Yes, I considered that. It will have a similar uniqueness rule, with one difference. Both players can have one out. Therefore if my opponent and I both control "The Skies" for instance, then I could Windstorm in The Skies to kill all of his and some of mine, leaving the stronger ones alive, but not affecting any in other Positions, or on the original battlefield. Of course, that means I have to either not make many Positions, so that the chances of both players having the same ones are higher, or make it so that opponents can move into your Positions, but can't activate the abilities of that Position.

Liosan

Ah, fantastic. Absolute genius. Why didn't I think of that!
Thank you!!

Added some more to top now.
Thanks Liosan!

Could use ideas too, if anyone has anything they think would be good.

Love the idea! How about something like this?

The Cabal Treasury
Position
Creatures cannot be cast into ~.
Whenever you successfully cast of gain control of an artifact or enchantment, untap creatures in ~.
Whenever a creature enters a graveyard, put a +1/+1 counter on target creature in ~.
, Discard a card: Move target black creature you control into ~.

For those not familiar: The cabal profit off of gambling, rare artifacts, and dark magic. Whenever something dies they absorb its death energy and become more powerful for it.

Shield and Shell 3WW
Position
Green creatures and black creatures can't be part of ~.
Whenever a creature in ~ blocks, all creatures in it gain banding until end of turn.
XXW: All creatures in ~ receive +0/+X until end of turn.

Venser's Worshop
Position
Nonartifact creatures cannot be cast or enter into ~.
Noncreature artifacts may be cast into ~.
The cost of artifacts cast into ~ is reduced by
Nonartifact creatures in ~ become X/X artifact creatures where X equals their converted mana cost.

I actually think this is one of the better ideas in the Card Showcase right now. There's a lot of mechanical goodness and flavor in this suggestion, which one can expand on. In fact, I think that if we go and work all the kinks out of the design, Positions might make a cool theme for a Community Set.

Anyway, here are my takes on the Position thing.

A Position inspired by Sun Tzu's The Art of War:

And another (sort of):

A way to move creatures from one position to another fast:

An artifact position:

A way to take entrenched creatures out:

And finally, a way to destroy positions.

So, what do you think?

Interesting idea. It has a lot of potential. It would make board sweepers much less efective for sure which is actually a downside I think. I would suggest that the base abilities of the positions to move creatures to a position should be only used as a sorcery.

Command should be cantrip.

I love Mobilisation and Siege Bombardier, though it'll have to be sacrifice to add a counter, not tap, otherwise it'll be rather overpowered.
The Position ideas are pretty good too, though I'm still working on the concept.

Currently, I have a rare, uncommon and common for each Position type (Airborne, Battlegrounds, Cityscape, Natural and Waterway), and there'll be one or two mythics. Right now I need a rare Airborne Position, dubbed Mountaintops; a rare/mythic 5 colour Cityscape Position, named Walker Academy (new name ideas are welcome on this one, very welcome); a common Natural Position - Forest Dwellings (?); and a common Waterway Position (tough one to think of a name, help!).

Some new examples, feel free to comment/suggest/scream:

A common

Uncommon

Rare

Mana costs aren't finished yet, still deciding those, so don't think Ambush is so cheap just yet.

This kind of reminds me of formations (or was it tactics? can't remember the name) in the Civilisation boardgame. In that game, if you had a tactic card (dunno, "Phalanx"), then each set of units matching a certain pattern (infantry-infantry-infantry-cavalry) gained you certain bonuses (increase in military power). So, how could this translate to MTG? Maybe integrating them with positions ("During your upkeep, you gain 1 life for each 3 Elves in Sherwood Forest"; or "Tap any amount of creatures in ~: ~ deals 1 damage for every Wizard and Goblin tapped this way to target creature"), or maybe as a separate card type...

Just idly speculating

Liosan

Sound like a nice idea, but kinda complicated.
Would be nice to see someone else do, though...

Also, I've added all the positions to the top now. Enjoy!