SideWinder

From MobyGames:
'This vertically scrolling shoot 'em up varies from the standard for this style of game, as it also features a degree of horizontal scrolling. The screen area moves across as you reach the edge of the screen and reveals a whole new range of enemies. These include lots of static turrets as well as cannon-fodder waves of enemies.

There are 6 levels and each level starts and ends with you travelling through a tunnel, and emerging on the other side faced with a new graphical setting, be it industrial, space or woodland. After clearing the last level the tunnel leads back to the first level, so there is no real ending to the game. There are no end bosses, instead each level ends with a more difficult part with a large ground structure and increased enemies and turrets. There are 3 difficulty levels to choose from, and a 2 player mode.'