200byteDemoChallenge!

Sure thing... not that mine is even near the best :P

This one has the tip included that Brucey suggested :)

g=99

Graphics g,g 

While KeyHit(27)=0
	' Detect key pressed
	If KeyDown(37) x:-5
	If KeyDown(39) x:+5
	If KeyDown(38) y:-5
	If KeyDown(40) y:+5
	
	' Determine edge
	x=Max(0,Min(x,g))
	y=Max(0,Min(y,g))

	' Create chase direction
	If x<a a:-2 Else a:+2
	If y<b b:-2 Else b:+2

	' Draw User Circle
	DrawOval x,y,7,7
	
	' Draw Chase rectangle
	DrawRect a,b,9,9
	
	Flip
	
	Cls
Wend