I want to propose the idea 
(though for developers it is not very good) that the game was one of three types of extraction of gold coins .1 daily quest to destroy the 30 bots award 5-10 (5 lvl) to 10 lvl 10-15, 20 lvl 15 -20 (how long it took to perform the task after its adoption), 2 Increase the loot of bots, gold coins and 4 Level 1 coin to 10 Level 3 gold and 16 lvl 5 (I do not know can lvl 6-16 with more coins) . to make an exchange of bolts (or as components called improvements) for example coins 250-1 500 - 3 coins 1000 - 10 coins), to be honest I do not think that the Developer's postavyatsya in the game is updated . donator upstream developer needed
(though for developers it is not very good) that the game was one of three types of extraction of gold coins .1 daily quest to destroy the 30 bots award 5-10 (5 lvl) to 10 lvl 10-15, 20 lvl 15 -20 (how long it took to perform the task after its adoption), 2 Increase the loot of bots, gold coins and 4 Level 1 coin to 10 Level 3 gold and 16 lvl 5 (I do not know can lvl 6-16 with more coins) . to make an exchange of bolts (or as components called improvements) for example coins 250-1 500 - 3 coins 1000 - 10 coins), to be honest I do not think that the Developer's postavyatsya in the game is updated . donator upstream developer needed