I agree, it's a challenge, especially when making a cohesive, continuous 'game'. So well done! Very fun.

What I did for my 'gameboy 3 level packs' were MEDIUM and HARD packs. 3 levels each pack, which play mostly identically, but for HARD I just added extra hazards. Exceptionally fast way to adjust for people's needs, doesnt break level design, and twice as many levels. Got the idea from Super Meat Boy - Light and Dark worlds (Easier and Harder).

Thanks! One of the hardest things is planning difficulty curve. I always end up making things too easy or too hard - getting a scalable middleground takes a bit of thinking! :)

Just completed this. Good difficulty ramp up. Last three levels were nice and challenging Amazing work!