Learn German: Verstößt du gegen die Regel, scheidest du aus, außer wenn es ein Fehler war. - If you violate the rule, you are eliminated, unless it was a mistake.

Außer wenn translates to "unless" or "except if", introducing a conditional exception to the rule. Außer dass means "except that", which introduces a factual exception to a statement (e.g., "He is nice, except that he talks too much"). Because we are talking about a condition that changes the outcome of breaking the rule, außer wenn is the correct choice.

How does außer wenn affect the word order in the final clause?

It acts as a subordinating conjunction, which sends the conjugated verb (war) to the very end of the clause. You can think of the phrase außer wenn as working together as a single block that triggers standard subordinate clause word order.

Why does the first clause start with the verb Verstößt instead of a word like Wenn?

This is a conditional clause where the word wenn (if) has been dropped. In German, when you omit wenn, the conjugated verb moves to the very first position. Verstößt du gegen die Regel means the exact same thing as Wenn du gegen die Regel verstößt, but it is a slightly more elegant or dynamic style that is very common at the B2 level.

Why does the middle part say scheidest du aus and not du scheidest aus?