A new big patch

So, It's a second patch and it is bigger than I expected.

What is new:

• the vision range of enemies is increased from 5 to 7 (whatever it means)
• improved turret's AI
• The algorythm of enemies spawning is changed
• added new background
• added player's upgrades and the corresponding menu (special button or Q key)
• added information panel (called on RMB)
•  few sounds added

Plans for the next patch:

• more sounds 
• more upgrades
•  (maybe) the collecting of resources