Those are some pretty creative cheats. While I don't think I'd personally enjoy playing the new invisible skin (simply because I'm not that good), I like your cheat idea of your character only seeing a few blocks behind and in front. Maybe instead make the whole screen black except for a small light source (i.e. visiable area) around your character? I also really like the concept of the Spike Bros. Are you imagining that they can only be killed the same way as a spike top (i.e. by a brick hit beneath their feet, a star, a kicked turtle shell, falling down a pit, or armor piercing weapons?) To answer your question, spike tops are more deadly than spineys not because they have less spines but because they have the hard shell of a buzzy beetle.