The rules in short
Popple is played on a grid of letter tiles. Trace a path through touching tiles (in any direction, diagonals included) to spell a word, then release to submit it. Each tile can be used once per word, words must be three letters or longer on the standard 4×4 grid, and anything in the 172,727-word dictionary counts. Longer and rarer words score more, and finding words back to back builds a combo.
The demos above cover the essentials. For the exact scoring tables, attack mechanics, and level thresholds, read the complete rules and the scoring guide, or jump straight into practice mode.