Cerrax

Nabeel is correct, you are looking for a standard square wave.  Here is an article that shows how to create such a sound in FL Studio:  http://howtomakeelectronicmusic.com/how-to-create-a-portamento-square-wave-lead-sound
There are also VSTs such as Peach ( http://www.tweakbench.com/peach ), which specifically emulate the exact square, pulse, and other waves from vintage video game sound chips.

I don't think the video is as important as the music. Mixing static images with video should be fine. Ideally you would want to show the music exactly as how it appears in the game so we can see how well it fits with the actual gameplay and atmosphere, but I don't think its 100% necessary. More than anything, I'd just like to hear some more variety in the kinds of music you show. Game studios want someone who will be able to adapt and work with exactly what their game is about, so you need to show that you are capable of many different styles of music.

Cool! Looks like you've done some great work on some pretty neat looking games!
For a 1 minute long presentation, its sad that the first 11 seconds are basically silent. This is actually a 46-second reel, not a minute!
I will say that while the songs themselves sound good, you're not showing a lot of variety here. All of these tracks have similar instrumentation, speed, and rhythm. I'd like to see different genres and instrumentation. Because so far the only thing i get from this reel is that you do well with strings and and light, bouncy melodies. Unless I had a very specific need for that exact style, I wouldn't think this video would alert me as a game designer that you should be the composer.
Great work tho and the games themselves look pretty cool! Congrats on the wonderful work you've done so far!

Cool! Looks like you've done some great work on some pretty neat looking games!
For a 1 minute long presentation, its sad that the first 11 seconds are basically silent. This is actually a 46-second reel, not a minute!
I will say that while the songs themselves sound good, you're not showing a lot of variety here. All of these tracks have similar instrumentation, speed, and rhythm. I'd like to see different genres and instrumentation. Because so far the only thing i get from this reel is that you do well with strings and and light, bouncy melodies. Unless I had a very specific need for that exact style, I wouldn't think this video would alert me as a game designer that you should be the composer.
Great work tho and the games themselves look pretty cool! Congrats on the wonderful work you've done so far!

0:00 - Trumpet sounds nice, if a little quiet. I would bring that out more. Listening to it a little more, the music box and piano are just a tad too loud. The strings and trumpet (and maybe even the distorted guitar slightly) are pushed to the back of the mix, despite the trumpet being the melody!
The writing itself is pretty good, it's got a good bounce to it and a very playful atmosphere.
0:24 - Drums and piano are a bit too loud here and the piano has no emotion to it. The rhythm here suggests an increasing intensity, but I don't feel it at all. The piano needs more velocity and less volume. Maybe boost the trumpet and strings a lot more here too?
0:48 - I really like the piano and trumpet parts here, but its using the same rhythm as the rest of the song, so the transition is kind of lost. Maybe experiment with a different beat that retains the driving train-like feel but is a noticeably different beat so that we don't get bored with it?
1:22 - The trumpets just kind of trail off here. Why? It sounds like someone bumped the mixer knob and faded them out too early
Overall, I like the melodies you have! Its a very playful song and captures the train feeling perfectly! But the layers underneath are very sparse and very simple.
There's a lot of repetition with no variation in the backing tracks. Try listening to each instrument individually and pretend you are playing that instrument. After playing the same phrase 4 or 8 times, it gets pretty boring. The audience may not realize it, but that means they're getting bored with it too. Try to alter the rhythm or dynamics or something to keep it interesting!
The mix itself needs some adjustment. The piano, music box, and drums are all too loud in some parts. And since they're all fairly short and/or staccato notes, it only makes the piece feel more sparse. I would also investigate adding a few more layers to fill out the sound. Maybe boosting those strings would help, or adding another instrument. Maybe even something as simple as bring the bass guitar into the mix more (I didn't even notice it until the 1:05 mark!)
I really like the idea you have here. I love the melodies, just the rest of the song needs more meat to support the fantastic start you've got!

That's actually a throwback to another Zelda game:
 
 
btw. hello everyone. Its been a while.
I generally refrain from using this phrase but Hyrule Castle is TOTALLY DOPE. It is easily the most perfect atmosphere from any Zelda game ever. The music, the enemies, the design, just everything is perfect.