Solar System++ generates a random solar system that provides a means to reach solar system edge
Large total conversion mods.
Map generation and terrain modification.
On the normal game, space ships would get a speed of -10km/s when they run out of fuel on a route to make sure you don't get stranded.
In my run (1642243051) I ran out of fuel and stopped at 0km/s on my way from Zzhora to Tchekor
I had thought I had fixed this issue at one point and added gravity to all the planets. Saw this on our run for the run this last weekend. Something to investigate, thanks for the report.