Glad to know it. Though I misunderstood you and thought that there is a problem with roamer script.
Now, about ants with original scripts marching towards your SpaceShip... You did not write "cmdline=position.x;position.y;range" in scene.txt along with CreateObject type=AlienAnt stuff. These original scripts always take these coordinates and the range from cmdline, and if you don't write any then cmdline gives to script 0 for each value. Therefore these scripts receive 0, 0, 0 values and ants go to 0;0 coordinates with 0 range.
Now, about ants with original scripts marching towards your SpaceShip... You did not write "cmdline=position.x;position.y;range" in scene.txt along with CreateObject type=AlienAnt stuff. These original scripts always take these coordinates and the range from cmdline, and if you don't write any then cmdline gives to script 0 for each value. Therefore these scripts receive 0, 0, 0 values and ants go to 0;0 coordinates with 0 range.