What game is this?

[adder]

im trying to remember the name of a game, it is in mame, and is i would guess a mid-eighties game.
it is top down perspective (birds eye view/overhead view), and you have control of some kind of tank/vehicle. the screen scrolls vertically as you move up the screen in your vehicle. there are roads to travel along (you can go left and right as well as up and down, but i think the screen only scrolls vertically). something which should help to identify this game: at the start of the game, i think your vehicle fires a large rocket type weapon which flies up the screen (making the screen scroll) and it explodes ahead somewhere, then the game starts. i think you can fire a few more of those rockets during gameplay if i remember.

does that jog anyones memory, what game is it? 

[Generic Eric]

Check here

http://www.shmups.com/xenocidefiles/arcade.html

[adder]

cheers it wasnt on that list but i found it now, it's called 'heavy metal'  by sega 1985