Very fun game! Pretty challenging and really cool! I found a few minor bugs like the music not looping, or the snail spawning red for some reason, but nothing that impacted the experience at all. As for the gameplay, my only problem was that amo costed too much and made it really hard to buy upgrades, so I ended up breaking the portal on the first attempt.
Overall, I really enjoyed playing and i love the mechanic of the portal breaking, it's such a cool idea! Great job!