Tally Turtle
Credits & license
Tally Turtle draws on the arithmetic and progression rules of Dopa Drill by gear_machine. We rebuilt question generation, step-by-step checking and local saves in Swift, created original illustrations of Tally and the garden, and added bilingual instruction, a prerequisite-based curriculum, the iPhone Duo sidebar, adaptive native music and haptics.
Read the original license and exceptions
Tally and the Luo Shu square
Tally draws on the traditional story of the Luo River turtle. Tally Turtle created the character, the kites, koi, swallows and lanterns in the garden, and the music, motion and haptic feedback used during practice. After a round, explore the Luo Shu square to see how each row, column and diagonal adds to 15.
Chinese typeface
Tally Turtle uses LXGW 975 Yuan SC for Chinese. The website serves WOFF2 subsets containing the characters used on these pages.