You captured the old GameBoy platformers so well! From the colour scheme, font, and the pixel art assets!! Really like the level layouts. Especially having secret areas to reach too. I was happy that you even implemented above-the-screen running like the old Mario games to find a hidden door! I was able to clear the first level easily, but the 2nd level got really hard. Some jumps had to be almost perfectly executed to avoid taking any damage. And having it so that if you cleared a secret in the previous level, certain blocks get hidden in the next one was genius! I only figured that one out since I got 1/2 in level 1, and level 2 had some outlined hidden blocks.

Some feedback:

• The jump SFX is a bit loud compared to the BGM. 
• In the 2nd map's secret room, it was almost impossible to jump over the double spikes with the low ceiling without getting hit.
• For the spikes that hit the player, I feel that maybe a solid outlike makes it easier to understand it was foreground. Since there's the spike outline sprites that shows hidden/non-activated spikes and platforms. Those ones stood out more to me and I thought I was supposed to avoid them as well.

super cute platformer!! everything feels smooth and i love the music choice (◕‿◕✿) nice work!!!!