Need help Finding an old favorite

[Zenmaster]

Can anyone help me find a game I played for hours as a kid, all I can really remember from the game is that it's a 2d side scrolling game, where you played as a green tank or some type of truck in what to me now seems like some underground world and you had to progress the level, the graphics were rough and pixelated! I've been hunting for this game for around 4 years now and I absolutely cannot find any information on it, any help is appreciated!