CC dance game?

m=peripheral.wrap("bottom")
ship={"^","v","<",">"}
xMax,yMax=m.getSize()
x=xMax/2-0.5
y=yMax/2-0.5
score=0
ex=math.random(1,xMax-2)
ey=math.random(2,yMax-2)
os.pullEvent=os.pullEventRaw

function printChar(x,y,char,ex,ey)
m.clear()
m.setCursorPos(1,1) m.write("score: "..tostring(score))
m.setCursorPos(x,y)
m.write(char)
m.setCursorPos(ex,ey)
m.write("o")
end

while true do
pos=0
if redstone.testBundledInput("left",colors.blue)==true then pos=1 if y>2 then y=y-1 end end
if redstone.testBundledInput("right",colors.orange)==true then pos=2 if y<yMax-1 then y=y+1 end end
if redstone.testBundledInput("left",colors.red)==true then pos=3 if x>0 then x=x-1 end end
if redstone.testBundledInput("right",colors.lime)==true then pos=4 if x<xMax-1 then x=x+1 end end
if pos~=0 then
printChar(x,y,ship[pos],ex,ey)
end
if x==ex and y==ey then
score=score+1
ex=math.random(1,xMax-2)
ey=math.random(2,yMax-2)
rs.setOutput("top",true)
sleep(0.5)
rs.setOutput("top",false)
end
sleep(0.5)
end