Cons: Would have liked a couple more stages, music/sound could have used a little work
The prisoners of war are all held in various buildings; you just blow up the building with a grenade/rocket and then stop beside it to let the prisoners walk out and climb into your Jeep - though strangely the Jeep is able to hold dozens of these guys. Some buildings will have a single prisoner of war who is flashing in color, and rescuing him is how you upgrade your grenade launcher. Three flashing prisoners will fully upgrade you to the maximum range rockets with the spread out cross-shaped explosion. These are really handy, as you can shoot beside an enemy and have the explosion take him out anyway, even through walls. You can also just drive your Jeep over foot soldiers to kill them, though this obviously doesn't work on tanks or anything else.
The six different stages are all pretty similar, though the setting is varied enough to not make it too monotonous. There is a swamp stage, one inside a base with an airfield, another that looks like ruins, etc. They are all presented in an overhead view and are all pretty linear. While there's a limited amount of scrolling as you drive from left to right, the bulk of the map always starts from the bottom of the screen and you head up to progress. After a few minutes of fighting and rescuing, you come across a helicopter pad where you can drop off your rescued prisoners and have points added to your score for each one. At certain score levels, you'll be rewarded with an extra life, and you may just find yourself needing them if you haven't played the game twenty times before. After you drop them off you will find a boss battle just ahead, and defeating the boss completes the stage so you can move on to the next one. Bosses are varied, ranging from destroying a few tanks, to taking out a helicopter or a battleship, to destroying an enemy base with multiple fixed-position turrets while destroying or dodging tanks and ground troops. Most of them aren't too difficult, but some (especially the last one) can provide a challenge.
The difficulty is pretty well balanced, the first level is pretty easy and it increases as you progress. Enemies start shooting more bullets at you, you start running into new types of enemies and they increase in number. It gets harder to avoid taking the occasional death, and dying resets any weapon upgrades you may have gotten back to the default grenade launcher. There are a few of the flashing prisoners in each level though, so you do usually at least have the ability to work your way back up to the better rockets prior to the boss fight unless you die near the end of a stage. When you die, you reappear in the same place and your Jeep will be flashing colors to signify you are immune to damage. This effect lasts around three seconds.
There is also a two player cooperative mode where you can play with a friend. The first player will always have a green Jeep and the second player will always have a red one. You both drive around on the screen at the same time, which makes the number of enemies easier to manage, but gives you less points per person when it comes to raising your score to obtain extra lives. You also have to get by with the same number of flashing prisoners for weapon upgrades, so it doesn't make the game so much easier that it's no longer a challenge. Usually when one of us rescues a flashing prisoner for the weapon upgrade, we let the same person grab the next couple of them as well so that we have one maxed out rocket launcher because it's much more helpful than each of us having a lesser upgrade. As long as you can stay alive it's a simple matter to let the other player grab the next few and then you're golden.
As I said before, Jackal is presented in a top-down, overhead view. The graphics are actually not bad for an old Nintendo game; the enemies are mostly detailed (except for the foot soldiers, who look rather like little white stick figures), the stages are varied in design and what few animations are in the game look smooth. I do wish the bullets fired by an enemy were a different color than the ones you fire though, especially when you're playing two-player and there are a lot of them on the screen at the same time. It makes it a little more difficult to avoid dying and losing your precious rocket launcher upgrades.
The sound isn't all that spectacular - the background music is pretty much the same through the entire game. It is upbeat and exciting, but there's really no variety. It does pick up in tempo a bit more during boss fights, but that's about it. There's also the scratchy rocket launcher sound, a mild explosion sound when you hit things, the standard helicopter sound when one flys by overhead, etc. Not a lot, and not much variety here either, but it's sufficient to add to the gameplay rather than detract from it.
There's not a whole lot to Jackal really, it can be played through in about an hour without much difficulty. Due to the length, there are no save games or stage selection screens; you just play through from beginning to end in one sitting. If you do lose all of your lives, you can choose to continue from the beginning of the current level and keep playing. You get up to three continues in total, and then you have to start over from the beginning of the game. All in all, it's a pretty fun game that I've had a lot of fun playing over the years. It still gets played every year or so like most of my Nintendo games. Like Contra or Ninja Gaiden, it's not too long and involved; which makes it easy to find the time to play through it when you're feeling that nostalgic itch. I've had my copy for many years, but you can still find a used copy on eBay for around $5. Well worth the money.