The idea is cool, sort of like tower defense game, but the towers can't attack and you must attack manually while linking to these towers. I read from the game page that there's a lot of bugs, and indeed the bugs listed there were in the game. I just wish that there'd be another version without bugs, because the idea sounds great!
If i can suggest something, it's to edit the square colliders of the trees so that only the ground/bottom part of the tree has colliders. I think it's more natural that way, because you should be able to walk behind a tree in real life.
Anyways, don't give up! Making games in 48 hours is pretty hard, so be proud that you submitted something in time :D