Background
As far as I can see (and at least in the official beta map-pool), there is currently only 2 types of 2v2-maps available. The first is the one where each of the 4 players is spawning in four "corners" of the map (lost temple, metalopolis, etc). These kinds of map heavily relies on early game rushes and more often than not ends up in two people ganging up on one of the others, resulting in a 2v1 map after the early rush. This was a problem, especially for double terran-teams which had a hard time reaching the team-mates base to help him reinforce.
The other type is the shared base-maps. Initially this was only twilight fortress, but with Patch 9 there came alot more. Now I am quite a fan of these maps really, since it gives 2v2 games the oppirtunity to evolve past the early-game stage. There are some slight variations on this, but most of them makes it easy to reach your team-mates base and help him out, or you could actually share the base with him, or you just could have an easily accesible shared choke.
Now I feel that these two map types have genuinely different playstyles. I started playing around with an idea for another type of 2v2 game, and here is what I came up with.
The map concept
The core idea of this map was to make early-game feel like two paralell 1v1's. You start off sharing a base with your team-mate but really unable to reinforce him due to the fact that there is a large chasm splitting your base in two. And you really don't have any way of crossing this gap untill mid-game at best. This basically splits the map into two parts, with two players duking it out on each side. However once one of teams actually manages to join their armies, they will have a huge advantage in taking out one of the other players. Combining the armies however will prove to be somewhat of a challange.
The map
A picture says more than a thousand words, so here are some pictures:
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Features
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Shared mineral line with your team-mate
Safe natural, but without gas
The only way to join forces by walking without first mining out your main (destructible rocks)
High-ground makes it easy for your opponent to stop you from opening up your own way to your team-mate
Strategies
Now without reapers, there is really no early game unit that can join forces with your team-mate . That means you will always need to keep in mind to have your own defences up since you don't really have any early game backup. If you tech to hard, you will get rushed. So early-game will be influenced by common 1v1 strategies. Once you hit mid-game however the options for reinforcing your team-mate becomes vast. Protoss could use colossus, or pyon power across the gap to warp in units on the other side. Zerg get nydus worms, terran gets siege tanks (which actyally have a long enough range that they can provide some defence as well) and all races get dropships.This is in addition to the fact that the middle rocks will probably be destroyed at that point as well. Air units might be a very viable option. Reaching the mid-game units however, might be a challange since you will have no easily defended natural with gas. So keeping gas sparse, we are forcing the players to get low-tier units which have a harder time reinforcing. Late-game play will be identical to most other 2v2 maps since all rocks have probably been destroyed, as well as your main have been mined out, finally opening up your base and you truly have a shared base.
The biggest design challange
The biggest challange that I have seen so far is the terrans. They have the ability to lift off buildings, which could really really ruin the balance on this map. However this is most definitly within what I consider cheese. And as all chesse-strategies, I feel that this should be a valid strategy, but with an obvious counter making it worthless if spotted. Now there is two variations on this. Either the terran float his CC over and starts his whole base there or he just floats his production buildings over. The first case is really not very valid since the natural expansion is lacking gas, and the forward expansion is very hard to defend (and a long flight-route, making him way behind in economy). The latter strategy, floating only the production buildings, will obviously put him in a very very vulnerable position. If the unchecked opponent responds correctly he should have an easy time rushing him and putting him out of business. Floating back and forth with his buildings making units on both sides I don't really is a very valid strategy since in addition to lost production time in transit, you will have to need addons on both sides.
Final thoughts
What do you guys think? I am convinced that there is some obvious flaw to this design which I haven't thought about which will completely ruin this map for any competative play. Other than that I think that this will provide for some interesting 2v2-games in which players will have to revise some of their old 2v2 strategies.