Field Wars is a bit like Alien in that you set traps in hopes that aliens (?) step on them. But instead of digging a hole for them to fall into, you bury a landmine. So when they step on the landmine, you don't have to go through the hassle of closing the hole back up, they explode and that's the end of them. But the trap is invisible so if you forget where you plant one, it will explode on you just as happily, taking one of your lives.

In addition to the aliens that hurt you, there's also an alien that wanders around aimlessly. It doesn't hurt you, but it is immune to your landmines. If it steps on your landmine, other aliens can't step on it and you have to plan your trap again.

Jamasuke, the bothersome alien that doesn't hurt you, has a benefit. If he sets off a bomb, there is a chance that a fruit will appear. You can really rack in some points that way.

Hudson Soft releases the same games for many platforms. I think they sometimes try to take advantage of a system's particular features when it's convenient. So most of their games have a few spoken words in key parts of the game if you're playing them on the PC-6001mkII and above. For Pasopia7, it would have been great if they had used the hardware dithering to give the appearance of more colors, but instead they opted to support the joystick cartridge. Well, that's something, besides Hudson Soft games the only game I know of on the Pasopia7 to support a joystick is Packings. It seems to me that the joystick cartridge is an inelegant solution compared to on-board joystick ports, because it's inviting developers to consider "well, how many people REALLY have the joystick cartridge?" It's certainly less than the number of people who own the systems, so when some portion of game developers decide not to support the joystick, fewer people decide to buy the joystick cartridge.