One of my favorite introcomp entries of all time, Hey, Jingo! has an oppressively present jungle setting and sinister hints of some horrific mystery going on.
That said, it is an introcomp game, and no finished version was ever posted -- so what's there is brief and short on gameplay, and the cliffhanger is necessarily disappointing. Not really a game in its current state, just a stub of something that might've been pretty nifty.