While short, I find this game to be an enjoyable take on the tower-defense genre. Being able to place the towers wherever you like is much less restrictive than the usual requirement of only being able to build in set areas or having to work in some kind of grid. If there's any changes I'd recommend you make, I think making the UI more in-depth would be nice, such as letting the player see how many enemies are left, or letting the player see the time between waves. Overall though, you've done good work here