The error states that you're missing a semicolon ; and looking at the code I see that you are missing one in the RocketLiftOff method. You have this:
liftOff = true
and you need to have
liftOff = true;
Minor typo. Whenever you see that error that's what it is, so you just to go through each line ending and ensure you have a semicolon where needed. I don't see anything else incorrect within the code.