I've just started doing Let's Plays of adventure maps. For my first choice, I've done your Mars Mission map. Enjoyable map! Episode 1 is up on YouTube now. We did manage to somehow miss out about 25 percent of the map in a later episode though. Oops!
Hey, tell me a little about the adventure map that you created? I rate maps and help promote map makers. You can click my signature for more info.
The adventure map is still in progress at the moment. I've made it quite big. Possibly too big. MCEdit rates it as 3 billion blocks or something crazy. The adventure area is a bit smaller. The rest is for scenery. I guess I love making landscape a little too much! I am a little worried about making people walk too far but, at the same time, I don't want to throw things in just to fill the space. I'm not sure on a completion date as yet as it is mostly just me working on it, with the help of a friend under my direction at times.
I would recommend nether portals or at least Minecarts
I still can't find your secret puzzle. I guess it has something to do with hex bot but I have no idea. I even had a look around in mcedit and noclip mode and still can't find anything!
It's possible to find the second half of the puzzle by stumbling upon it and several people have gotten to the conclusion. But no one has yet satisfactorily proven that they solved the first portion.
I'm pretty sure I've given this clue somewhere, so I'll just say that Hex does seem to be unique among the other bots.