Hey. So good job for the first gaming vid.
About the length, it’s fine but it’s just personal preference, some people like it shorter, some longer.
Editing was pretty good, you chose the best moments and it def made me smile a few times and got in a better mood lol
You can include outro but also put end screen such as links to your playlist or the best related vid and subscribe button. Make audience to stay on your channel and binge watch all vids and this way you can gain a potential subscriber.
Also put more effort into thumbnail, get creative with it, look at other popular content creators of your niche (halo on your case) and look at their thumbnails, that can give you some ideas. You can use web service called “Canva” for that, it’s free, and I personally use it.
And also I see your description box is empty, full it up with important information, out key words in it, this way you can improve your SEO and more people can find your vid.
So with all that being said, good luck man!