Well because there isnt much going on. Maybe if you added more content it would get better, maybe even an objective instead of just "survive"
you have to wait 5 minutes than there comes a boss
there is also a leaderboard and the aim is to survive as long as you can to get in the top 4
Oh sorry I didn't know that. But still, if you add a lot more content to this game it may be actually very good!