A long time ago, we invented a simple game called Hurkle and published the first primitive version of Hurkle as a computer game in People's Computer Company, April 1973. We have invented new versions of Hurkle called HurkleQuest that use colors of the rainbow as "fuzzy feedback" clues. We have played HurkleQuest in classrooms, by USPS mail, and by email. Since 2004, we have run many tens of HurkleQuest games for first-grade to sixth-grade teachers and their students. Here there be descriptions of HurkleQuest Play-by-Email games.
HurkleQuest on the Number Line.
HurkleQuest in Quadrant 1.
HurkleQuest in Quadrants 1, 2, 3, and 4.
HurkleQuest in Oregon.
Math is joyful when teachers and students play together, learn together.