How to get multi-state: a maze with funky doors

IMG_0001.PNG The basic idea of a multi-state maze is that a visually perceived position in the maze can have different ‘states’. This means that being in a particular position in (the visual presentation of) the maze does not mean that you are in the same position of the state-diagram of the maze. In other words: although it might seem that you are on the same position, you can be in different parts of the ‘real’ maze. This abstract principle needs to a good mechanism to work as a puzzle. One approach is to use doors that selectively block a particular part of the maze, and which can only be moved in certain positions. As always with multi-state maze-design, this approach was pioneered by Robert Abbott in his Sliding Door Mazes. A variation on this theme (though I think completely independently developed) is the iPhone game Space Trap, shown here to the left (iTunes link).

[Update 6 February 2009] Space Trap seems to have disappeared from the app store, but today another version of the same puzzling principle became available: Open Doors. Different developers, but there seems to be a direct connection between Alcomi (the company behind Space Trap) and Armor Games (from Open Doors). All a bit confusing though… [end update]

IMG_0002.PNGHere to the left is an enlargement of the first part of the path of the puzzle (the bottom of the full level as shown to the top right). There are four doors in this small segment: without doors it would only take seven moves to pass through this part, but with the four doors it takes 36 moves!

The doors have a somewhat strange logic, but it quickly becomes intuitively clear how they work. Each door is hinged at the little diamond in the corner of the tile. A door can be pushed open from outside this tile by walking through, with the effect that the door moves over 90 degrees around its hinge. Coming from the other side (‘inside’) the door cannot be passed. When the door is open, and when you then move from the ‘inside’ to the ‘outside’, the door automatically closes with your move (i.e. you always close the door behind you).

The trick is to open the doors that are originally blocking your passage, because you need to pass them from the inside. For example, the central trick to solve the small enlarged part is to open the leftmost door. The solution has a very nice repetitional structure (using N-E-W-S notation):


The opening of the leftmost door is the step south after the second repetition. As can be seen, it takes a lot of preparatory work to open the crucial door. Once opened, it is a quick walk out. This principle actually makes really great puzzles, and I can only encourage you to try out Space Trap if you are interested in multi-state mazes.

On the visual side, I find that the doors might be a bit more clearly indicated (e.g. by different colors). Also the usage of white lines for internal blocks is a mystery to me (see picture in top right). Further, some of the tiles are differently colored, or even transparent (see the blown-up section). These variations are completely irrelevant, however, and this let me astray in my first attempts (I didn’t dare to step onto the transparent tile, because I though I would fall down). Also the buildup of the difficulty of the puzzles might be fine-tuned, maybe including a few more ‘simple’ puzzles to get a better feel for the dynamics of the doors. And just a final detail: unfortunately it is impossible to freely select the level you want to (re)play. For such puzzles, in which there is no time-constraint or other arcade-like element, it makes much more sense to simply present a list of all puzzles to the user and let him/her select which level to try.

However, such interface details are easy to resolve, and it shouldn’t restrain you from trying out this nice variant of multi-state maze design.

IMG_0004[Update 26 February 2009] I have had some time to play Open Doors (shown here to the left), the replacement of Space Trap. This game explicitly credits Ozzie Mercado (“SoapAintNice”) with the development. He seems to have made this game as a flash game online in March 2008 at Armor Games. Another interesting puzzle concept from this same person is EnDice. He seems to be a really innovative puzzle designer!

I guess that the development-group Alcomi simply took his idea, made some more levels, and published it as Space Trap. There has been another dispute between Alcomi and Armor Games (as I have described in this post), which seem tbe have been resolved both at the same time.

Open Doors is a really interesting multi-state maze concept (as I have described above). And this original version also resolves the two major complaints that I had about Space Trap: the doors are better visualized, and the levels build up more slowly. The only downside of this puzzle is the movement control: you have to touch the tile next to the square to get the square moving. Hopefully they use the swipe-gesture in a next update! That would make the game so much more enjoyable.


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