Definitely had me playing for a while trying to get the highscore but you unfortunately have bugs. I can confirm the same bug Riven just posted, and I believe it occurs because you give yourself a deadlock, which if you recall you programmed to kill yourself. So at this point you could either let the person slide out either path or call this thing a "feature" and say just don't do that

I also ran into several bugs where my line would not fill in after completing a box, as these two images show:


I also noticed that if you're going towards one of those "sliders" that go along the walls, and you try to trap him but end up just on top of him (if you hit him exactly instead of the wall behind him) you get past him and he doesn't die. Or at least this seemed to be the case. And there was one other bug which occurred which I can't remember right now, but it killed me somehow, I think like I died when some other guy touched a wall I had already built, but there were some other weird glitches slightly prior to that. I got this and the error from the 2nd image I posted both in one game which killed what I thought was finally going to be a good highscore. :\