I have tried to make a function to add 1 degree, repeat 90 times, but it only runs once because of the run once condition. The same problem occurred when I tried to use an OR block to save on events, but the OR block doesn't work with run once.
If I don't use run once, my ship starts going in circles when it hits a corner.
Also, I ran into a problem in Firefox and IE, it seems like the turn rate is tied to fps, so when fps drops the ship starts swimming off the edge of the screen.
Live Demo: http://www.mbcoffice.com/construct/index.html
Edit: Ack links don't work. Typing them out in plaintext