It didn't work in Firefox. But I was able to play it in Chrome. I also couldn't really figure out what I was supposed to do in this game. A tutorial would have been nice.
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It seems that a lot of browser playable games are giving problems to some people. I guess that has to do with specific configurations / versions, because I was able to play them without issues on my pc.
I didn't want to make it too evident, and let the player discover what was needed on its own, but I see now that was a bad decision. I should have explained it on the game's readme or tutorial.