Old School
Mongoose
This ties in with my comments on my dreamed up homebrew setting in another thread. I think the MgT2 rules would have to be tweaked more for an Expanse type setting.
The deal with the Epstein drive is that is doesn’t have a specified limit on what acceleration it can produce. Every ship with an Epstein seems to be able to faster than humans can survive. Torpedoes have Epstein's as well, and because they have no crew they can reach much higher acceleration, although I don’t remember if a limit is ever specified. So either you have an Epstein or you don’t. No differences in size of drive as a percentage of the ships volume are apparent.
A setting with everyone getting a 1G handwavium drive plus high burn thrusters on warships, would be plausible, but I wouldn’t call it the Expanse setting.
The PDCs being gauss rounds vs lasers isn’t as big a deal. Short range beam lasers per the traveller rules would work fine. Only difference would be that pdc can run out of ammo in an extended fight.
The deal with the Epstein drive is that is doesn’t have a specified limit on what acceleration it can produce. Every ship with an Epstein seems to be able to faster than humans can survive. Torpedoes have Epstein's as well, and because they have no crew they can reach much higher acceleration, although I don’t remember if a limit is ever specified. So either you have an Epstein or you don’t. No differences in size of drive as a percentage of the ships volume are apparent.
A setting with everyone getting a 1G handwavium drive plus high burn thrusters on warships, would be plausible, but I wouldn’t call it the Expanse setting.
The PDCs being gauss rounds vs lasers isn’t as big a deal. Short range beam lasers per the traveller rules would work fine. Only difference would be that pdc can run out of ammo in an extended fight.