Patch notes v.90.21

In this update, I added two more new upgrades:

• Upgrade for the drilling rig (increases mining speed)
• Purifier upgrade, each new upgrade speeds up cleaning
• Changed color of upgrade icons

A few words in conclusion:

Still, I will release updates as new content comes out, I can't work on the game all day right now due to the very high ambient temperature.. it's just hot as hell here. And yes, first I will add all the upgrades, and then, when they are all in the game, I will add a change in the appearance of machines and conveyors when upgrading. So now most likely I will release small updates with new upgrades. And by the way, if someone noticed a bad balance somewhere - let me know, I will review and fix it, thanks.