With Mountain King, what’s probably happening is that you’re tricking the game into interpreting random bits of memory as level data. (eg. the memory that holds the game code)

This “Real Life Tron on an Apple IIgs” blog post goes into more detail on how that sort of thing works:

http://blog.danielwellman.com/2008/10/real-life-tron-on-an-apple-iigs.html

Better to ask your local pharmacy for a bottle of 99% isopropyl alcohol or your local hardware store’s paints section for 99% denatured alcohol. (Automotive shops may also have it.)

No matter how damp you make your Q-Tip, that stuff will evaporate quickly, leaving no residue behind, and the only reason it’s 99% is that 100% alcohol sucks water out of the air. (Random Wikipedia wandering taught me that it’s called a hygroscopic mixture.)