Grumpy is loosely based on ITC Grouch by Herb Lubalin. Design is slightly heavier than Grouch, and many glyphs differ notably from Grouch. It is a display typeface with very tight tracking, and more than 2000 kerning pairs for overall even color.
Letterspacing method is TNT (that is Tight, Not Touching); a very popular type treatment int the seventies and eighties. Grumpy has some stylistic alternate glyphs.