1- You have to add much more detail.
2- the idea isn't very unique. Add things we wouldn't imagine you would.
3- The corn is lacking things, it's really just a tree and chests, I don't really have any ideas for it but definitely you have to improve it.
4- you have a train. Great! Like basically 50% of other maps. Again, to make a Sg map good, you must make is creative.
Overall it's not the best but I definitely see potential inside this map. No hate on what I said, it's criticism, it will help. Take what I said into context and this map still has a chance I would say. Also, get more friends and terra formers and definitely redstoners. As you know, to make a Sg map and get it accepted is a lot of work. I am currently working on a quarter quell map and let me tell you it's hard. We've been working with around 10 people and things are coming fast and slowly at the same time. Take your time don't rush and I can definitely see this map as a great map.
Have a great day!