Yeah, I work on some games too. I know how important it is. I also have some ideas for a difficulty curve but you probably have it being well worked on.
Oh, definitely! If there is any kind of place i could suggest it i will, but for now i'd just like to say that you should need a special platform to build on the underside of an island, copper should be found at the bottom of the island, iron should REQUIRE a stone pick and you should need to sacrifice a lot for a lightning stone and, finally, silicone should be rarer than it is, and sand should be able to be picked up from somewhere.