Tower Defence submission for the GameDev May & June Challenge.
 

Featuring:

5 unique structures  
4 Levels of challenge
30+ Unique shapes to break.
Sounds FX & Firing Animations.

Instructions:

Toggle Game Screen Size by pressing f

The game is divided into two parts, tower placement & wave action

During Tower Placement you can place towers, walls and crystals. 
Select available structures and left click to place, right click to remove.

During Wave Action you can upgrade towers by Left Clicking on a selected tower:
All upgrades increase tower's firing rate 

During Wave Action you can chose a tower's target priority by right clicking on a selected tower and selecting the priority of your choice.
If you select user selection as a target priority then any shape you left click on becomes the target for all towers which are set to user selection.

Lastly, you can click the U in the top right corner to activate any free upgrades you may have.
Earn free upgrades by refusing to build all available tower types during tower placement.

Enjoy the game and thanks for playing