Very interesting idea! I like the idea of letting all players be at any point on a shared timeline. One thing that I think might work better than forcing a time sync periodically for all players is to let anybody be at any point on the timeline until they choose to "activate the time jump device" to synchronize their time with another player. At that point ONLY that player would instantly jump forward in time/game state to match another player. This could be a little tricky because it would require maintaining the "time jumping" player's position relative to whatever planet they are near since that planet will have moved at the time the player wants to jump to. The big advantage would be that you and a friend could fly to the mun using any time warp you felt like and then instantly "meet up" for a real-time joint mission by time jumping to each other. This would be doubly sweet if you could peek at a player's current time state to figure out where they are on their time. Or better yet see a "ghost" of a player in the future if they are near the same planet you are to make it easy to do a time jump to them. I think the multiple players at different points on the same timeline idea + a "time jump" feature to let players meet up with those in the future might solve the "multiplayer time warp is logically inconsistent" problems and be pretty easy to understand/use.
