Dropzone is a series of shoot 'em up video games that are bi-directional, horizontally scrolling shoot 'em up in the style of Defender. It was designed and written by Archer MacLean, his first commercial video game. In fact, "Arena Graphics" is just a shell name for MacLean himself. It was released for the Atari 400/800 and Commodore 64, then later ported to the Nintendo Entertainment System, Game Boy, Game Gear and Game Boy Color.
Source: Wikipedia, "Dropzone", available under the CC-BY-SA License.