I ran around for a long while avoiding everything until I found (a) my whistle and (b) a chaingun.
When I restarted I found I already had a gun, but it probably makes me chill faster anyway as games felt shorter, or more fun. I fond some horizontal exits/entrances to not let me through. Maybe I wasn't jumping to the right height; it felt like a bug but I was freezing so can't be sure. I suppose you have several screens randomly arranged and supposed to all interconnect with minimal player jostling. Or you just arranged all the screens by hand and I found the invisible wall.
Anyway, great game. I'd like to think the power ups are meta-progression because I die soon after finding just one per game.