Pretty cool game, but a little confusing at times! I quite like the game at its core, as the feeling of speed was nice and the game, while simple, had an addictive nature to it. Also, I love the amount of little touches the game has, such as being able to pick on the penguin at the start and it makes a little noise, along with all the nice visual/audio effects like the death animations, going into tunnels, the speed lines, and so on. Overall it does feel quite smooth and polished.
The main issue I have with it is that the mechanics are a bit confusing. As said, the main mechanics of dashing and jumping through the course to get to the end is fine and feels great. But the additional aspects to the game are weird.
For example, fish are a bit confusing and the game can't quite seem to decide what to do with them: first it tells you not to get them since it makes you fat and slow, but then the game gives you 'points' for getting them which seems like a positive. This made me think I needed to get them for a high score, but just not get too much so as to not be able to finish (aka five of them). But then I noticed that the score numbers were technically getting redder the more I ate, so I figured, ok, I guess it really is a bad thing and I should avoid them. But then I noticed that some courses can't be beat if DON'T eat fish because it needs you to go slower, while other courses can't be beat if you DO eat too many fish since you don't have enough speed to make jumps. It just feels unfair and confusing: do I eat them or not? I just want consistency. Maybe you think it's part of the challenge to figure out whether to eat or not to finish a course, but I hate that kind of trial and error: fish should really just be an extra score thing, I think, and not softlock you into not getting through a course if you don't guess right the first time.
Moving on from fish, there was also weird stuff like the slow-mo. It's a nice addition, but why in the world does the slow-mo bar keep draining even when I'm not holding it down? You'd think that as long as I stop using it, it would recharge or at the very least not keep draining. It takes what could be a fun mechanic you can use sparingly here and there and makes it this ultimate choice where you have to use it all now at once or else waste the whole damn thing.
Finally, there was also some other nitpicks like how I had no idea how to get out of the hat menu once I was in it: how the heck do you exit? I just mashed keys until the game started somehow.
Overall I'd say that this game has a lot of promise: I think the core mechanics of speed and jumping through courses is fun and smooth. It's just that the other mechanics of fish and how the courses are laid out are a bit confusing and unfair at times. Once those are all settled, I think this could be great!
Oh yeah, and I'd love some little sliding sound effects.