Speed Ladder

Each tier gives you a passage and a time limit. Finish the passage before time runs out and you climb to the next tier, which is a little longer and gives you a little less time. Run out of time mid-passage and the climb ends there. There's no fixed finish line, the only question is how high you can get before the ladder catches up with you.

Early tiers are forgiving on purpose, so you can find your rhythm. By the middle tiers, the margin for hesitation disappears, and the later tiers pull from harder vocabulary on top of the tighter clock. Your highest tier reached is saved as your personal best.