Hey guys, one of the developers here.

Thank you all so much for all of your feedback! I never thought this game would become so popular.

It seems that our server is more or less overloaded right now, so AJAX requests for new levels are sometimes failing. This appears to be the cause of the bugs that some of you have experienced where levels load incorrectly or are overwritten by previous levels. Sorry about that. :-/ We will work on making the game more robust in the case of failures like this.

If you want to run the game locally, you can clone it from https://github.com/AlexNisnevich/untrusted and follow the instructions there.