just typ /grav
then open then click :P
i had the idea from a guy on picwin.tk and decided to make my own.

menu @gravity {
  sclick:grav 1
}
alias grav {
  if (!$window(@gravity)) {
    window -pdk0 +fxnbt @gravity -1 -1 200 450
    drawrect -nf @gravity 1 0 0 0 200 450
    drawdot @gravity 04 20 100 70
    drawtext @gravity 04 arial 10 11 60 Click to Play ->
    %grav = $iif(!$1,10,$1)
  }
  else { 
if (%_x) && (%_y) { 
      drawdot -n @gravity 1 20 %_x %_y
    }
    if ($1) {
      drawrect -f @gravity 1 0 0 0 200 450
      %__y = $mouse.y
      %_x = $mouse.x
      %ball = 0
    }
    inc %ball %grav 
    %_y = $calc($int(%__y) + %ball / 10)
    if (%_y > 405) {
      %_y = 405
      %ball = $calc(%ball * -0.7)
      drawtext @gravity 04 arial 10 $r(8,170) $r(50,350) Bounce!
    }
    %__y = %_y
    drawdot -n @gravity 04 20 %_x %_y
    drawdot @gravity
    if ($left($calc(%grav / %ball),4) != -2.4) { 
      .timergrav -m 1 25 grav
    }
  }
}
on *:close:@gravity: {
  .timergrav off 
  unset %_x %_y %__y %grav %ball
}