If you ever had to prepare multiple permutations of tests to distribute in a large class and you had to prepare the permutations by hand, you will agree with me that it is a really tedious task and that it is really hard to do it without introducing some mistakes in the questions. I have to administer mid-term tests for students sitting next to each other in such a close way that it is in fact impossible not to see what your neighbours are doing, even if you try to be honest and avoid looking at the neighbouring papers. On the other hand I also administer very short quizzes (10 minutes) to be done at the end of a practice sessions in a computer room. For this I also had to create a lot of different versions of the same exam in forms that can be published through the web.
Given the frequent nature of these tests, it is almost unavoidable to prepare them in the multiple choice format, otherwise there would be a need of a lot of time dedicated to grading. In my case, I use mechanical grading by having the students enter a form and having a machine scan the form and grade the answers. In the case of the web form exams, the responses are saved in a file by a cgi script, and grading is done by another application (in my case I use a statistical package to process the data and compute the grades).
For the final exam, I also like to hand in other types of questions where students can write and be evaluated based not only on their final result but also on their intermediate results and methods used to solve the stated problem or case. For the final exam I use then a combination of multiple choice questions and short answer questions. I teach technical subjects such as statistics, but of course this type of exams can be used by any subject. In the case of technical subjects it is nice to interact with TeX/LaTeX.
So I thought that it would be a big contribution to have an automatic system to prepare this type of exams, so that the instructor could concentrate in thinking about useful exercises and questions, and not dedicate most of his or her time in formatting the papers. I looked around to see if there was any software that could do this, and I found some commercial options.
The only free system that I found was the Much system. Manyex was inspired, and used as its initial code, by Much http://fourier.math.uoc.gr/~mk/much/) developed by Mihalis Kolountzakis. This is a simpler system, where only multiple choice questions are allowed and the idea is to prepare a lot of permutations of the same tests, enter the responses in a file and have the program grade it for you. Manyex inherites its basic structure, but it extends the capabilities introducing much more structure in the questions, allowing for the construction of more complex exercises composed by different questions, but taking the grading completely out of the system.
Some of the ideas of Manyex were also inspired by the LaTeX package examdesign.sty which I used originally to prepare my exams.