So what can I say what hasn't been said here?!
It's like a new exciting version of Angry birds combined with this thrill of constant mayhem in the end. I would say that definitely develop this on mobile and start selling it, you'll be magic some money for sure!
It's so fun to play and probably one of those games that I will come back to multiple times, adding the high score table there as well is genius in a game like this! The portal throwing and multipliers were really well thought and I just have to congratulate you already for winning the whole thing! :D
Simple, fun, easy to learn hard to master, just all in all 10/10.
Could have made the story better if there was a small cutscene or something there in the start to show where the monsters are coming, but other than that I wouldn't have anything to add! Kind of like Angry Birds have/had if I remember correctly about the pigs stealing the eggs, so it gives kind of a more meaning to why you're slinging these birds into walls.