easy for kid, challenging for adult

the blue on black skin is the easiest to play (best contrast for speed sake).
the sound and light of *new* burners is so easy to understand that a young child can play on his/her own without parental supervision/explanation.

unfortunately, there are only 100 or so level, and Ive circled them half a dozen times already ..

SophSF about Gas tycoon 2, v1.5.5