The xrotate and yrotate commands tend not to work exactly as you'd want, but I don't see anything obvious. Here's my space flight sim, but altered to take joystick controls.
rem Space Flight Code, by The Darthster!
rem Initialisation
sync on
sync rate 30
hide mouse
autocam off
rem Make a terrain to fly over
make matrix 1,10000,10000,50,50
rem Set up initial positions and angles
x#=5000
y#=200
z#=5000
theta#=0
phi#=0
thruststep#=0.1
rem Set up bullets
dim shot#(10,10)
for i=0 to 9
make object sphere i+1,5
next i
do
rem Mouseclicks control speed
`if mouseclick()=1 then thrust#=thrust#+thruststep#
`if mouseclick()=2 then thrust#=thrust#-thruststep#
rem Now the joystick button controls speed
if joystick fire a()=1 then thrust#=thrust#+thruststep#
if keystate(17)=1 then yaxisstrafe#=yaxisstrafe#-thruststep#
if keystate(30)=1 then xaxisstrafe#=xaxisstrafe#-thruststep#
if keystate(31)=1 then yaxisstrafe#=yaxisstrafe#+thruststep#
if keystate(32)=1 then xaxisstrafe#=xaxisstrafe#+thruststep#
rem Shooting
rem Putting in a firing delay
if mouseclick()=4 and shotrecently#=0
shotrecently#=4
for i=0 to 9
rem If the bullet is 'dead' then create a new one
if shot#(i,0)=0
rem Alive
shot#(i,0)=1
rem Current position
shot#(i,1)=x#
shot#(i,2)=y#
shot#(i,3)=z#
rem Current velocities plus velocities provided by the gun
shot#(i,4)=xvel#+(sin(theta#)*cos(phi#)*20)
shot#(i,5)=yvel#-(sin(phi#)*20)
shot#(i,6)=zvel#+(cos(theta#)*cos(phi#)*20)
rem Angle
shot#(i,7)=theta#
shot#(i,8)=phi#
rem Life
shot#(i,9)=30
show object i+1
exit
endif
next i
endif
if shotrecently#>0 then shotrecently#=shotrecently#-1
rem Update the bullets
for i=0 to 9
rem If the bullet is 'alive' then move it by it's velocity
if shot#(i,0)=1
shot#(i,1)=shot#(i,1)+shot#(i,4)
shot#(i,2)=shot#(i,2)+shot#(i,5)
shot#(i,3)=shot#(i,3)+shot#(i,6)
position object i+1,shot#(i,1),shot#(i,2),shot#(i,3)
shot#(i,9)=shot#(i,9)-1
rem If it's just run out of 'life' then 'kill' it and make
rem it available for use again
if shot#(i,9)=0
hide object i+1
shot#(i,0)=0
endif
endif
next i
rem Mouse movements control angles
`theta#=wrapvalue(theta#+mousemovex())
`phi#=wrapvalue(phi#+mousemovey())
rem Joystick controls angles
rem Change the value (currently 0.005) to set sensitivity
theta#=wrapvalue(theta#+(joystick x()*0.005))
phi#=wrapvalue(phi#-(joystick y()*0.005))
rem Decay the thrust so you don't go really fast
thrust#=thrust#*0.9
xaxisstrafe#=xaxisstrafe#*0.9
yaxisstrafe#=yaxisstrafe#*0.9
rem Accelerate the velocities (this took ages to work out)
xvel#=xvel#+(sin(theta#)*cos(phi#)*thrust#)
yvel#=yvel#-(sin(phi#)*thrust#)
zvel#=zvel#+(cos(theta#)*cos(phi#)*thrust#)
xvel#=xvel#+(sin(theta#+90)*xaxisstrafe#)
zvel#=zvel#+(cos(theta#+90)*xaxisstrafe#)
xvel#=xvel#+(sin(theta#)*cos(phi#+90)*yaxisstrafe#)
yvel#=yvel#-(sin(phi#+90)*yaxisstrafe#)
zvel#=zvel#+(cos(theta#)*cos(phi#+90)*yaxisstrafe#)
rem Some friction to stop you going too fast
xvel#=xvel#*0.99
yvel#=yvel#*0.99
zvel#=zvel#*0.99
rem Simple velocity
x#=x#+xvel#
y#=y#+yvel#
z#=z#+zvel#
rem Screen display
text 0,0,"X velocity:"
text 0,20,"Y velocity:"
text 0,40,"Z velocity:"
text 0,60,"Theta:"
text 0,80,"Phi:"
text 0,100,"Thrust:"
text 100,0,str$(xvel#)
text 100,20,str$(yvel#)
text 100,40,str$(zvel#)
text 100,60,str$(theta#)
text 100,80,str$(phi#)
text 100,100,str$(thrust#)
rem Rotate and position the camera
position camera x#,y#,z#
yrotate camera theta#
xrotate camera phi#
sync
loop
