Four runners, one floor full of coloured bricks. Pick up only the blue ones and run up one of the three staircases: every step costs a brick and turns blue, your own steps are free and other colours you build over — but run out of bricks and you are stuck. Bump into a runner with a smaller stack to knock theirs loose, and watch out for bigger ones. Finish in the top two to reach the next race, with more floors, longer stairs and smarter bots. Free, no sign-up — play right in your browser.