A mystery quilt is a project where you are only given one part of the pattern at a time. Sometimes the cutting instructions are given at the time of the fabric requirements. Sometimes, you get cutting instructions with each step. At the end, you get the instruction of how to put all of the parts together. It is like the reveal of a painting at that time since you have no idea how your fabrics will play out in the final design. It is a lot of fun. You work at your own pace and you keep the top. One word of advice: When the instructions tell you NOT to use directional fabric - DON'T. (Ask me why I know this. lol)

I totally agree about swapping in country/region. I belong to German quilt forums as well and they do lots of group projects. Postage is SO expensive (plus there are the customs forms to deal with) that it is not fiscally feasible for me to play with my German quilting sisters.