Hello Sonaos, its me again. I just can't help but give a more in depth comment/crit on this lovely image. I was drawn to your image by the combination of cute and appealing characters. I'll try to break this up into points so I don't ramble too much:

>THE GOOD<
*The layout (or composition) is very strong, two characters with two backgrounds side by side is very effective and it clearly aids your idea of a "spoof" videogame boxart. It works well. I wouldn't say its a very original layout- I've seen this type of thing before, buy hey "if it ain't broke, don't fix it"
*Your pencil sketch is clear and sharp. It looks as solid as an inked drawing and is a perfect springboard for the colours.
*Character designs. You nailed Sonic's design with great precision, his eyes are the right colour and you even remebered the golden buckle on his shoe. Sonaos is a wonderful OC, because while he's not just a simple recolour, he clealy has the "Sonic style" I don't normally like OCs much, but he's genuinely appealing.
*colouring. The picture is sensibly and consistently coloured with a clear attempt at shading shadows. You've shown a light source at the top of the pic and your characters have a bit of depth. Its a good effort.

>THE BAD<
*Sonic's left (his left) foot. His foot is drawn coming almost straight out of the page, when he's actually running diagonally accross the page; it looks like his ankle is waay twisted. In my opinion it would have looked better if the foot was drawn showing more of the side and less of the front.
*If I was being picky, Sonic's spines should be slightly bigger, but I understand that this would have meant they crossed into Sonaos' half of the pic and messed with your layout. They don't look bad as they are.
*The line (or division) between the two backgrounds is wavy. Its not clear weather this is intentional or not. If the BG division is meant to be straight, grab a ruler next time. Otherwise you could make it more deliberatley wavy. You could even make a feature of it! Way back in the day I did a similar type of image and had the division between the two backgrounds made up of interlocking pieces like a jigsaw... I'm rambling, sorry. Anyway, its not that bad, but there's scope to make it better.
*In general, the texture of the colours is a little bit rough, which doesn't suit the videogame style very well. I KNOW coloured pencils are very difficult to get smooth, but it IS posstible. Practice and patience are the two biggest things you need. Nobody can wave a magic wand and make you a pro. You've got a very good start here, you can colour very neatly, and some of the flat areas (like the green hill behind Sonic) actually look pretty good. Things you might want to try on future projects;
You can vary the pressure with your pencils to get different shades.
Different types of strokes yield different results, even stokes in the same direction work well for flat objects, small circular movements with varied pressure can be used to describe a more complicated surface.
Try blending different colours together, its great fun, will expand your palette, and can lead to some really great colour combos.
Lastly and most importantly type "color pencil tutorial" into the deviantart search bar. Thank me later ^_^

>SUMMARY<
You draw VERY VERY well for such a young artist. I'm not trying to put you off, I want to see you do better.
Brush up with your coloured pencils, take your time and practice!
You have a strong artistic vision, and I enjoyed seeing your ideas put on paper
I look forward to seeing what you can cook up next time.