I'm about to make a hyper-casual game for mobile devices, haven't decided yet what engine to use for native app but current prototype is built using pixi.js since that's a tool i'm most familiar with. Basic gameplay is revolving around nodes (let's say planets) and a ball that is rotating around a node, can detach from it, go to free fly and attach to another node if it's close enough (like a small space object that get's into gravity field of another large object). Right now i'm not using any physics engines but would like to simulate some gravity behavior in a more realistic manner but leave some other aspects in a simplified manner. Can you provide any guides, books or anything else that would help to dive into the problem of realistic and not so gravity imitation in games? Thanks in advance!