Feed the Animals by Shooting them [Left-Mouse-Click , Mouse Position]. 

You Cannot Continuously Fire, Bullets Take Time To Load.

As You Feed The Animals, You Collect Currency,.

If You Have Enough Currency, Upgrade Options Will Start To Appear (above the player). Clicking Them Will Activate The Upgrade.

The Upgrade Options Available Are -

1 [LEFT] - Automatic Feeders - They Feed Animals Which Are Closest To Them Within A Range.

2[MIDDLE] - New Animal - A new Animal Pops Up.

3[RIGHT] - Expand Your Area.

(Currency required increases for each upgrade)

The Game Ends If Your Currency Is Below 0.

The Highest Animal Population You Are Able To Reach Is Your Score.

Software’s Used 

Godot - Game Engine 

Pixelorama - Pixel Art 

Bosca Ceoil - Music 

BFXR - SFX

font download link - https://opengameart.org/content/minimalist-pixel-fonts [CC0]