lvl 20 bit buggy, the red cube wont as smoothly slide over placed pink blocks as expected.
lvl 23 is an extreme jump in difficulcy compared to the previous levels. I like that level a lot, but there should be something shorter before that (I used only green blocks there btw, thought I might need the others but didn't - challenge to my fellow gamers :) ).
Add a second run with less blocks. I didn't need to use ~30% of them during almost all later levels.
The green blocks are a bit annoying. Make four of them, one for each direction at game start and let them reset to that direction once you respawn. Same for the tnt timer. This will allow us to race against the clock in later versions.
I agree to @JamAttackMusic s comment below to keep a selected block selected after death - unless you want to make a (very) hard mode where all blocks are reset on death.