Shattered Pixel Dungeon - This is a variant of the original Pixel Dungeon. This version is better balanced and has more content. Available for PC, tablets and phones. Source: over 2 years ago

Pixel Dungeon and it's many of it's modded versions are free of grinding and financial transactions. Some modded versions have grindy typical RPG aspects added to them, but most don't. Most if not all mods should be available if you are open to using an android emulator. Pixel Dungeon classic is unforgiving and will do it's best to kill you. Shattered Pixel Dungeon is a much more expansive mod of the original that... Source: almost 3 years ago

I played a PC game called "Osmos" (http://osmos-game.com/) like back in 2012 or so. It has all this electronic ambient music as the soundtrack. However, the soundtrack is not created for the game. Rather, the soundtrack is a selection of pre-existing tracks already produced by a few electronic music artists. The link above is one of my favorites. Source: almost 2 years ago

You can physically demonstrate orbit with some fabric stretched over a frame, but I really think video games are going to be your best friend here. Osmos (Free demo, $5 full) is a great starting point that uses simplified gravity in two dimensions. Orbit (Free app, $5 on Steam) is another, similar game to introduce orbit. Once you've graduated to three dimensions, Universe Sandbox ($30, $20 on GOG) will really... Source: almost 2 years ago