So, I bought the little controller, and I probably spent an equal amount of time--if not more--playing it as I did my Wii. I learned about a few neat NES games I would've never heard of otherwise through this little controller, such as the (in my opinion) superior version of Tetris by Tengen, Yie-Ar Kung Fu, Karateka... but the game which wowed me the most, which I still play to this day on occasion, was Sqoon.
Sqoon is a horizontal shoot-em-up like Gradius, except in a novel-for-the-time twist, you control a little pink submarine underwater instead of a spaceship in space. Aside from having a unique setting, Sqoon is also a fairly unique shoot-em-up all its own.
A little intermission on the title screen, complete with an SOS in Morse code, says that Neptunians have invaded the Earth and are melting the ice caps. It's up to you to pilot the Sqoon submarine and beat back their assault, before it's too late!
In actuality though, it seems you may already be too late! Each stage starts out with a peaceful little tropical tune as you travel over an underwater city, appearing to be based on various locales from across the world.
Still, those Neptunians have to pay. How does Sqoon fight these alien invaders? Well, you have two weapons at your disposal in Sqoon--a torpedo that shoots straight ahead, and a depth charge that travels diagonally towards the sea floor. While the torpedoes and depth charges can both hurt any biological enemy, you need to use the depth charges specifically to destroy flashing things which your torpedoes have no effect on.
The main enemies in the game are the Neptunians, which are cute little alien things which travel in all sorts of unique ways. These big one-eyed creatures travel in a loop-de-loop across the screen, for example. The enemy patterns keep the game fresh and interesting.
Towards the sea floor is a container with a flashing cap on it, which we need to destroy with the depth charges. What's in the container?
Captured earthlings! We need to rescue them before they drown or get eaten by the killer whales which always follow Sqoon around.
Once you have 9 earthlings aboard Sqoon, a ship appears on the surface of the ocean where you can deposit them. Your reward is either a stronger weapon or more fuel, the latter of which you can also get from bombing crabs with depth charges.
And that's the basic formula of Sqoon--shoot alien sea creatures and free their captives. The levels get longer and longer and the enemy patterns get more and more complex as the game goes on. Being an early NES game, it's very arcade-y, but it's a lot of fun! The colorful yet grim setting is also a neat anachronism which I think adds to this game's charm.
Sqoon doesn't appear to have been very popular at the time, as it hasn't had any re-releases or really any mention at all outside of its initial release, which is a shame as I think it's one of the better horizontal shoot-em-ups out there.