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

There's always World Anvil. They have a free member tier that includes decent basic tools/features. But I just checked the site, the lowest paid tier has a few improved features and its $54/yr USD plus they have a 50% coupon for the next day or so. Source: about 1 year ago

Always: when in doubt: change password asap and make sure to reset via the original site, not a link in your email. (worldanvil.com looks like worldanviI.com but it is not. Some fonts don't show any difference.). Source: over 1 year ago

Hi there! To create a new world, go to the global dashboard (worldanvil.com, or click the World Anvil logo on the top left), go to the "Your Worlds" tab and click the create world button on the right. Freemen, as the other commenters said, can have two separate worlds. Source: over 1 year ago

Such an engine already exists at worldanvil.com, including a discord channel for just such an enterprise. I am a lifetime Sage there, so if you end up using it, let me know. I can help you get the project together. Source: over 1 year ago

Per sources from worldanvil.com, Darandra's Thrill is a keelboat which Tirah the Shark uses for smuggling. I adjusted Darandra's Thrill to fit my campaign and turned it into a gambling riverboat. This map represents the main gambling hall where visitors descent from the main deck. Despite being a gambling hall, the room emanates calm spiritual aura and many visitors chill here, smoking from waterpipes, listening... Source: over 1 year ago