Changes in physics
A new type of component (and cargo) added: Defense Grid (which uses Defense Ammo). Engines and fuel are now used for different purpose: now they are used for approach.
But first, defense: mathematcis got simpler: one defense grid destroys one incoming rocket. So if your ship has more defense grids than opponent ship has guns - you won't lose any component. Which is easier to estimate by AI, but makes the game a bit less fun.
Moreover, approach and avoid commands cost some fuel - so now AI attacks less frequently, and player tends to be more conservative, too. You're less likely to "approach aggressively" a smaller empty ship just for fun.
Space docks now accept only fuel, and a new random encounter added - a space dump - which converts any component to Cargo Bay (and destroys cargo bay), and any cargo - to fuel.
This way it's much easirt to build "a spaceship of your dreams", which raises a question: now what? Probably, we should start colonising some asteroids, but that gets out of "1d-space" idea... into 2d, at least :) Note to self: it's possible to do with Poisson disk sampling or Perlin/Simplex noise. Second approach is heavier on calculations, but doesn't require storing position of each point in savegames.
Due to above changes, currently there is no trading and ability to use engines to avoid rockets - these features are likely to return in future updates.