I'm not quite sure what ratio of character stamina to health potion necessity you were going for, but I get the sense that you definitely over- or undershot it.
I get the weird screen too (all the text shows up as vague rectangles, and the landscape seems to be only half-rendered). It seemed to work fine after going fullscreen once (the bottom-right corner option; the response with three boxes is "yes")--both fullscreen and the normal size worked just fine thereon.
I did manage to get to zone 2 with the blank screen, though, which is more than I can say for quite a few full-visibility runs.
People are getting really mad at this game but for me the double jumping and wall climbing both work perfectly well.
It's kind of odd, since I'm not normally all that great at wall jumping.
Yeah, the wall jumping is irritating because you have to press against the wall--this meant I clung to overhangs when I just wanted to walk somewhere, but during the wall-jump sequence it's very difficult to constantly reverse directions. If nothing else, don't put the last jump of the screen right above the beginning, because I almost stopped playing after falling because I really didn't want to do the whole sequence again. Otherwise, though, this was pretty fun, especially for one whose development was so compacted.
 "Super Adventure Pals"){kind=icon}
 "Idle Sky"){kind=icon}
 "Pwong 2"){kind=icon}
 "The Valley Rule"){kind=icon}
 "Dream Hopper"){kind=icon}
 "Hello Worlds!"){kind=icon}