Hey! Nice game! It is a bit too difficult, in my opinion.
I have some suggestions for improvements, if you don't mind:
- Animate the character. Just simple run cycle (4-8 frames) would be enough. This works not only for the visuals of the game, but the whole feel of it. If you don't want to animate the character, just use simple shapes and colors and you'll get nice minimalistic aesthetics (Thomas Was Alone);
- My personal and very subjective nitpick - create art in one resolution and don't scale it. It prevents you from having pixels of different size on different objects. Right now, fro example, one pixel on the background > one pixel on the obstacle > one pixel on the character. Having pixels of the same size will make the game look more accurate;
- The camera often hides something important from the player. For example, the player stands on the platform and doesn't see what's below, so if he decides to jump down it is a leap of faith. And if there is some hazard and the player dies because of it then the player's mind goes "I didn't see the spikes there -> this means the game is unfair". Consider adding some offset to the camera. Also you may want to watch this litlle video about cameras in games. There are a lot of videos and GDC talks about it, but this video is quite short and gives the majority of the useful information;
- Make the hazards' colliders a bit smaller than the hazards visually are. Most games use this trick. If the player's mind thinks that he can make the jump without touching the spikes than he'd most of the times label the game "unfair". Even if the game perfectly calculates the bounds of every collider, leave the player a chance to make imperfect jump but succeed. I always considered game developers to be a helping teacher for the player;
- Some obvious things. Add particles, effects and sfx ( ironic to hear that from a guy, who didn't have time to add sfx to his own game :D ), anything to make your game feel juicy;
- Consider reading this article by Scott Rogers (old but gold) and wathing this video by Seth Coster on designing platformers. I promise, both will be more than helpful for you and your future games.
Overall, this is a good submission. Congrats on comlpeting your first jam, good job! I hope that this jam will not be your last)