AFAIK, 2300AD and Twilight:2000, v2 were to be very similar. I never had the former, but I rather like the v2.2 development of T2k. 2300AD now (via Mongoose) uses the rules from Traveller (that is, 2d6 for everything)
Now, Twilight:
200 would be about Roman legionaries, cut off behind German (or Dacian or Persian) lines after Legio V had been overrun by barbarian horse-archers. The last word from the legate: "Bona fortuna. Estis solitarii."
