How it works
Stroop Snap is a 30-second speed round built on the Stroop effect: a colour word appears on screen, printed in an ink colour that often doesn't match what it spells, and you tap the ink — never the word. A correct tap is worth +1, a wrong one is −1, and the next word appears instantly either way, so the round is really a running tug-of-war between reading (automatic) and colour-naming (deliberate) for as many trials as you can get through in 30 seconds.
Difficulty moves two things at once. The colour pool grows from three (Red, Blue, Green) to four (adding Yellow) to six (adding Purple and Orange), so there are more buttons to scan and more ways for a word to disagree with its ink. At the same time, the share of trials where the ink actually matches the word — the easy, no-conflict ones — drops from 45% on Easy to 30% on Medium to just 20% on Hard, so higher difficulties don't just add colours, they also give you less of a break between genuine conflicts.
Each round scores from its net correct answers: net is your correct count minus your wrong count (never below zero), and that net is measured against a par for the difficulty you played — 18 on Easy, 16 on Medium, 14 on Hard — which becomes a round score out of 10. Solo sessions and both Challenge modes are three rounds each, so a perfect run tops out at 30.