Thank you again, I'm glad you appreciated the update! I will get to fixing the level select issues.
For the level 8, that's a design oversight on my part, sorry. I wasn't sure whether to make an instant unlock on the level completion, or to require a score threshold, at first. Currently, The next level is only unlocked when you beat the score threshold of 1000 x Level number (i.e. 8000+ on level 8 to unlock level 9) - but I haven't made that clear anywhere yet (whoops). if you unlock the next level for the first time though, it should say "new level unlocked" next to your score.
I'm thinking maybe to remove the score threshold, because it's unclear and acts mostly as an artificial difficulty, when it matters, and impossible not to beat in other cases. On the other hand, it's an 80s arcade game, and unforgiving difficulty is part of the authenticity! 😄
Well done on getting to level 8 though, I think you have done the best from everyone I've seen play so far :)