Thanks for your input.
Actually I was thinking more of a metroidvania for the full game rather than level based, It'll be a long process to get it done tho... As for level design, I've already made some changes, I'm trying to introduce mechanics first in "safe" environment and then add challenge with something to lose, to some extend I feel that I've accomplished this, but not fully (for example, later when water is introduced in the mix, the first platform kills you, I've changed it so you'll drop in water and have to get up from there rather fast, since there's internal timer before you drown)