the game is fun, i played it for about 3 months now, at beginning its really fun any enjoyable, you have allot of things to do, as you progress its still pretty fun, i open the game 2-3 times a day, collect the income, make new animals and so on... but as you progress further, you need more and more zoo tokens, you can get them by completing quests or watching ads when they appear, at beginning you dont need many of them, but later on you need 500+, and considering you get about 20 a day if you play like me every day and open the game 2-3 times to collect income and complete quests that reset every 8 hours, either way it takes allot of time just to get some of those zoo tokens so you can expand, also not to mention that as you experiment with new species, they take longer and longer time to finish, i got almost the last species(the last one is A and the one before is M class) and to research just 1 random animal it takes me about 1-2 weeks.... the game started from being one of those games that you can play every day, to a game that you play few times a month... also this last update that they done has allot of bugs and the new system they added and new look, i dont like it.