This was one of my favorite 2600 games. It has a lot of charm and character, and can be challenging without being frustrating.
One drawback to this game is that there are 48 different types of games you can play, and you absolutely need the manual (or a scan of it) in order to know which mode to choose. You can have either one or two players, either 2 or 4 flying enemies, side enemies or no side enemies, have enemies bullets shoot stright or random, and choose from 3 difficulty levels, and freely mix & match options.
You can actually just take random guesses at the settings though. Two things to remember are that even numbered options are 2 player while odd numbered ones are single player, and that higher numbers mean higher difficulty.
Without the cave critters, control is pretty standard. Use the stick to go left or right, and the button to fire up at the flyers. The addition of the cave creatures though adds an odd control to the mix: Pressing up or down on the joystick shoots left or right.
What has always been one of the biggest attractions of this game for me is the sounds. The death sound of the flyers is is a quintessentially 80s video game sound, and the sound of the gun when shooting at the cave critters can really only be described as a digitized farting noise. I often play this on an emulator, just to be taken back in time. Seeing the images on the screen & especially hearing the distinctive sounds always takes me back to sitting there in front of a 13″ color TV, having just watched He-Man and Heathcliff, and having a Happy Meal Lego kit sitting in front of me.
Here’s a commercial for it: