I totally agree with @oxford. This kind of payments and donations exist in all kinds of games (mmorpg,moba,idle,fps etc etc) even though you PAY for them to begin with. If developers didn't have anything to gain for their games, you would still play games with the quality of mario on sega. If you don't want to pay nothing is stopping you to keep playing for free. But some people actually want to support the developers.
This is the first browser game I'm playing where there is an everyday update and the developers actually care about our opinion and you all keep complaining.. It's a game, not astrophysics. Just play and have fun! :) Btw it's a great game, so far one of the best idle games I've ever played! Keep up the good work and I hope to see more games from you!
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We are very happy that you like the game :) With your support we can keep developing it :)