There's a serious lag and it kind of sucks when you can't see a platform until you jump on to it and then immediately land on an enemy. When clicking on the menu, the titles don't change so I was confused as to whether or not it was actually registering my action. Not to be pesty but I find that kind of important. Upon selecting start, it didn't notify in any way that it was selected afterwards, and then lagged a bit before starting. When started it continued to lag while I aimlessly tried moving forward and then registered it (or loaded?) all at once and I jumped forward rather quickly as if hammering the pad lmao. I find the art style rather intriguing and very cute. It's a nice thought on a game, and I'm sure with just a few adjustments it would be awesome!

There is an unbearable lag that makes this game very hard to test, i have tried it on 3 different web browsers and the outcome is the same.

This looks like a school project, am I right? High school/intro class in college? It looks pretty good! It must have taken a significant amount of work, and (if it is a school project, forgive me for being presumptuous) I'm sure you were graded very highly. You created a cohesive and functional project, and I think you guys should be really proud of that! (The animation on the cat is very smooth, btw, good job.)

But something about this idea is just so cute and appealing to me that I wish you would expand upon it! I've always wondered what happens to my cat when she goes tripping on cat nip...

I'll admit it's unlikely for a school project--trust me, when I'm done with one of those I don't want to touch them again with a 10-foot pole, so I know the feeling--but if you ever wanted to create an actual fleshed-out/polished product from this, here are some things to consider:

UI
1. For some reason my mouse does NOT change to a pointer when I hover over the loading screen options? User feedback (i.e., letting the user know that the game recognizes the user's actions by giving them on-screen indications that their action has been registered) is very important in games. My mouse should at the very least change to a pointer, and a good idea would be to animate the options (as in, maybe the text just gets bigger, wiggles a little, whatever) when the player hovers over them.
2. Game pauses a lot when I click an option on the loading screen, like for more than a few seconds. Gamers are impatient, okay, we can't wait that long! I could understand if it happened when I clicked Start (BUT, again, user feedback is important; you need to say something like "loading game..." so the player knows that their click on start has been registered) but for other simple options like instructions or credits that needs to be fixed.

GAMEPLAY
1. This is where you're gonna be able to create something really good! I think you could have so many different options here to make this more than a bare-bones platformer. All I'm doing now is jumping around, avoiding enemies. Maybe I could fight them? Spit hairballs? Maybe I could eat more catnip to get faster/stronger? Maybe when I eat catnip the world gets trippier/distorted art style? You have so many possibilities here, but you're going to need a main mechanic other than just jumping around--and if it's only just jumping around, you need something to make that experience unique. "A mythical space journey" sounds so cool! You've gotta make the gameplay as cool as that description!
2. The jumping mechanic itself might need to be tighter. Right now it feels that I move a bit too fast and too high. One platform didn't work as well (as in, when I jumped on it, I fell through it).
3. I feel like I need a story here! How did this cat get on his catnip... What does he want to accomplish, besides getting home... what are his hopes and dreams! Details! I need to empathize with my cat as he gets beaten by meteors!

AESTHETIC/ART
1. The cats on the loading screen are just SO adorable, and I think that art style suits a cutesy/tongue-in-cheek game like this. Right now it's obvious that you have multiple contributors, and their art styles don't mesh completely. While having clashing/surreal art could be an interesting aesthetic for a game a cat high on cat nip, I think it would be hard to pull off well... The art as you have it now, though, for the cats and the enemies is very good. You just might need to make the other art work with it.
2. My cat has a white box around it when it moves, which seems glitchy. Also, you shouldn't have a lives count right next to the cat. It confuses the general layout and just gets in the way. You should probably have it up in the corner. The player's eye should be focused on the cat, not the red text next to it. Also, DON'T do it in Times New Roman. It should be in a cutesy/bubbly font for the game.

Anyway, that's all that comes to mind right now. Of course what I say isn't law, just my personal opinion about what makes a good player experience through years of playing games. Don't take this as me dismissing your hard work or saying "this is terrible blah blah blah"! I think you did a very good job for what this is! It just could be better, like everything could be.

I wish you luck!