Oh, it´s only one sprite causing problems, because the name of the file has a special character and the browser has problems for use it.
You can play the Gd Games version (https://gd.games/kolde/the-cosmic-postman-and-the-sec), free of this problem (with only a stupid bug; if you die in the first level, you’ll respawn in third level, hehe).
Thanks for the feedback ^^