The arcade segments in It Came From The Desert are some of the most awful I have ever seen. Even homebrew stuff that I made years ago was better.
I like the crosshairs-style one where ants are chewing the flesh off screaming people. The overhead parts aren't too terrible, either. I must admit that the side-scrolling stuff is bad, though it becomes more tolerable once you earn that "special move" (which happens pretty early in the game, thank goodness).