Sky Kid is a NES port of the arcade game with the same name. You play as the Red Baron or Blue Max, both famous World War I pilots.
Your mission is to fly through hordes of enemy formations, pick up a bomb, and drop it on the enemy's headquarters or main weapon. It is noteworthy that in this game, unlike most shoot 'em ups, you go left instead of right; that was a surprise when originally released.
You have some tricks at your disposal to help you succeed. As in most shoot 'em ups you have some weaponry, but the bullets only travel across half the screen before disappearing; there are no upgrades. You can also perform loops in order to get behind enemy planes chasing you (as it is impossible to turn around), and while moving up or down your plane will tilt up or downward slightly, allowing you to shoot diagonally. If you're shot, you can rapidly mash buttons to recover before crashing to the ground, but the more you do this the harder it will be to survive.
Once you pick up the bomb (you have to fly close to the ground to get it to attach) you can no longer perform loops until you dispose of it. Eventually you will reach a large fortress, battleship or other "base", which is the ultimate target. The closer to the centre it hits, the more points you will get.
A short time after this a landing strip will appear which you must land on (just hitting it at full speed will work). Later on, there are some levels with multiple bombs and targets to destroy.
After beating all the levels, they repeat, much like other arcade games. There's only one level that's different from the others — in this one there are a number of targets spread around which you must shoot without any trouble from enemies. Aside from the main features the game has some amusing quirks.
For example, in certain levels, if you perform loops near a certain background object something will happen. Looping near the sun will turn it into a moon and make the whole level dark, and looping near the Statue of Liberty will make its skirt blow up. Multiple levels also have dancing women who turn into what appear to be cats when shot, which seems like a bizarre occurrence.
Sky Kid is amusing for a few levels, but will get old quick. The enemies' different shooting styles (exploding shots, missiles, etc.) will quickly get the better of you, and it's just not long enough to last you a while. There is a simultaneous two player mode where you can try to annoy your friend, but even this isn't really that fun. The lack of music, aside from an endlessly repeating 15-second tune, also contributes to its low score.