A simple Tower Defense game I made in two weeks.

You can drag the items on the left side onto the sockets in the middle. When you drag the item on the big slot on the top the Item will define the type of turret that's on this socket, on the smaller slots it will upgrade the turret according to the effects seen when hovering over it.
Later you will also get new sockets to place along the track.

Warnings:

• You are able to place items into full slots, the old item will be lost.
• When a item doesn't instantly snap into a slot, move your mouse, clicking doesn't help in that case.