Stage 1 of LOGOSGBITS: seven trials in definition — the first act of reason, and the root the rest of logic grows from. A definition must fit exactly the right cases, every one of them and nothing else, in words you already understand. Everything after this depends on getting it right.
Each trial is locked until you clear the one before it. Every level scores out of 1000 — 600 for accuracy, 400 for speed — so speed alone can't clear the bar; you have to solve most problems, and quickly. Reach 650 to unlock the next.
You can build a definition from its genus and differentia, and test one to destruction — asking what else fits, what is wrongly left out, and whether the word has quietly returned to itself. Every stage above this one rests on that skill.