I found Outpost has many improvements over some of the ports of Missile Command: the explosions are circular, like the arcade not that horrible pixellated diamond shape. The running speed is much much better, no more laggy cross-hair movement, this version is blazing fast. Ammo dumps are destroyable positions on the planet surface, so defend those as well as your cities and main ammo supply, or you're going to have a bad time. The High Score table is writable to disk, which really increases the replay value of this version. And thanks to the trainer, you can wipe the list in case your kids beat your best score!
Graphics consist of fairly blocky sprites, and a plain black background along with the usual vector missile attacks and a smaller variety of enemies. But otherwise it's a great conversion, and well worth checking out.
Posted by @hayes_maker