If you're looking for a short, but sweet and fun game to pass the time this is it. There is some progression as you need to do levels in order to get crystals to unlock things. The gameplay loop is simple and enjoyable, stay alive while killing monsters, getting relics, and gold. The longer you last the more you're rewarded. This definitely fits the mobile vibe more, I could see myself waiting for something and pulling this up to play. I did however play on my PC on the browser, which was just fine as well.
Fun little game that I recommend you try out. :)