I need help identifying an arcade game I played in the 80's.

This is the only game I have been addicted to in my life, and it would be awesome to show it in some emulator to my buddy who always played with me. I am not a gamer at all, so I don't know precisely all the terms etc, but I will try to describe the best I can. I have been searching for this game online for ages, but there is not a good way to search for it, all is too vague...Tried http://www.arcade-museum.com/ and http://en.wikipedia.org/wiki/List_of_video_arcade_games but no name rings the bell.

Let's see:

1. It's a multi-directional shooter, according to http://en.wikipedia.org/wiki/Scrolling_shooter#Scrolling_shooters. The player sees the scene from above. The spacecraft is always in the center of the screen, and you can turn it in any direction, so it can point at any degree. It shoots in the direction it is pointing, so it can shoot in any direction,

2. The spacecraft has two weapons: a sort of laser/bullets, shot from both sides, and they go parallel to each other. And some guided missiles. When you hit a target with the bullets, if it not destroyed, the missiles acquire it, so the next missile will follow the target and possibly hit it.

3. The spacecraft is shaped like an almond, quite round. Background is like some future land, with land and also constructions.

4. Enemies are of many sorts, all are machines, some move and others are fixed to the ground. They shot different things at you I think. Some special enemies were a sort of buses that appeared always from behind shooting lots of missiles.

5. In the end of each level, a very big enemy mothership would appear from behind you, and you had to face it, shoot bullets so you could acquire missle target and shoot missiles to kill it. The mothership would shoot lots of missiles at you that you had to avoid. Once the mothership was killed, the level was done, and your spacecraft would move itself some distance, in the direction you were when the mothership was killed. You could see the trace your spacecraft would leave in the air (like it was moving in slow motion).

6. In a couple of levels, I think 2nd and then 9th or something, there was a small plane (yes, like a normal plane from 1940) that would cross the screen (bottom up direction), if you killed it you got an extra life. One of the times you would catch the plane when it was cruising above a river. You got also extra lifes by reaching X points, so usually you would get many lives until a certain level, where things get harder, and then start loosing them.

7. Playing two good players, a game could last up to an hour. Player took turns to play, not possible to play both at the same time.

EDIT:

1. I forgot to mention, this was played in an upright arcade machine, not pc or handheld device or anything. You had a stick to move the spacecraft and two buttons for laser/missile.

2. It was definitively before 1990!

3. Here some pics from some of the answers that look somehow similar: This has a similar background, imagine one like this but with much less green and more brown/grey This looks pretty close actually! a little more futuristic buildings maybe, and a bit darker colors This looks similar too, but mine has stuff from the future, not WW2 weapons. And a spacecraft, not a chopper, and always in the middle of screen. A last examle, as the first one, would need darker ground, but looks similar.

Added the bounty, let's hope it helps...

thanks for all the upvotes guys, they will fund a bounty :)

FINAL EDIT: got the right answer, THANK YOU ALL!! This is fucking great :)