I recommend downloading the high quality version (click on the time near the top to go to the download page).

1) With the retro thrusters, they should either be excluded from the game, or be activated after the player has stopped moving for a couple of seconds. Otherwise making the ship remain completely stationary would be a real pain.

2) With the missle lock, an easy solution would be to add a toggle “permanent lock” key. The player could lock on to say, a Destroyer and then press “L”, and no matter what the player moves his mouse over, it would remain locked on to the Destroyer. Then he could either press “L” again, or kill the destroyer to reset the game to automatic targeting.

Anyways, great game and keep up the good work.

Also I decompiled it to see why there was so much lag on my computer, and even delayed responses to key presses, and key releases. There are a lot of untyped variables (untyped variables or variables typed as * (same thing) are easily 4x slower than a typed object, and for things like int it’s more than 10x as slow), and unnecessary copying of variables all over the place.
In the sequel, you should explicitly type every variable you create, and you don’t need to make a copy of the XML before you write it to the ByteArray (ByteArray makes a copy of the memory at that location, so when you do that, you have three copies in memory, this can lead to a memory leak).

With the whole, length thing, that’s the good thing about non linear gaming. Make it so that people can grind, fight random battles. Maybe have a warp module, which can jump you to different sorts of missions (protect, kill x, collect x) which at different stages of the game have new real missions, made by you, and otherwise, have generic random starmap missions.