There are 3 landtiles that are pretty useless, desert, ice and peaks. Peaks are always useless. Desert can have resources, but is otherwise junktiles. Ice by a river can have a watermill and sometimes ice have a resource. So I thought if we have a city next to a desert tile, but proper irrigation next to it, there should be a small % every turn to change the desert to a plain. And ice could turn into tundra by the same example. I don't want healthy tiles to change, just the useless ones. We have global warming in the later game that take away tiles for us already, so why not have the same system to give us a tile here and there in the earlier game, just by chance. Mountain peaks, I don't know what to do with them. If I could just blow them up and change them to a simple deserthill, I would be happy. I really hate those tiles and in my last game, there wasn't one single city without losing out at least one tile, most cities more. Terraforming is not what I ask for, just a little fairness to crappy maps, contra global warming, which will make those crappy tiles multiply.