It's the first time I have seen someone made a Tower Defence game as a jam submission because I thought it's a nut too hard to crack but you made one and it works pretty good but among the development you left some mistakes. I grewup with them and I think you could add or change some things to make your game better
Wave pause mechanic is broken, I think it should work by freezing location of various ways of opening a door and stop your door from attacking but simply by changing the speed of the game I managed to unfreeze the game and proceed with waves whenever I want without worrying about timer. Valve, please fix!
I also think towers need some more love and more changes. While picking towers there should be information about their properies like damage and range because it helps new players make better decisions and you don't have to guess how each tower works while in a pinch. Some balancing work is also needed
I liked the gameplay but I think you chose something too big and you couldn't finish everything you planned on time. To be honest this game is barebones, you have basics done and ready but it's not enough to call this a finished game. You have found a gem but you left it dirty and unrefined. Nontheless, what you created in given time is truly fascinating and I believe your next game will bee even beter!