Sometimes when I'm playing Cities: Skylines I wish I didn't have to please anyone. I wish I was allowed to just sit back and make mountains and nice rock formations. I'm sure there's a mod for that, but there's also Planet – a quiet, relaxing planet-molding game where you don't need to worry about sewerage management (or anything else).
At first the toolset seems a bit limiting: there are four textures – forest, water, city and grass. You're able to adjust the size of your brush, and most importantly, you're able to raise the height of of any surface. It's surprising how flexible this small toolset is: you can make geographically complex planets if you want, but it's also nice to just watch the land rise and fall, and to imagine what it would be like to live on a planet shaped like a lollipop (yeah, I made a planet shaped like a lollipop).