I'm stuck and will have to start over, I think, because I apprently used my blue key too early and now can no longer get through the trap door above the 4th floor.
Problem on level 18: I sometimes required a run-up to push the spikes. Some of the grey blocks forming the floor were uneven by an imperceptible amount, causing me to be flung into the spikes without warning.
I'm not sure if my computer is just havin issues, but when I tried to type my name, not all the letters worked. The only ones that were working were e,t,i,p,g,d,s,a, and m.