Thank you for your feedback. We went through several different iterations of the game with different mixes and matches of the mechanics. Through playtesting we found that prior versions were too difficult for players so we decided to make it easier and more accessible for the jam with a tutorial level and a relatively easy main level. There was also a scaling system that would gradually make the game harder to prevent the kind of tactic you tried but we found a major bug in it last minute and had to remove it. The upgrades system was also not completely fleshed out due to the time constraint and only one person working on it, nor was it playtested extensively.
Balancing the game was the biggest challenge when developing it; we did the best we could for the time we had but it certainly could have been better. There are some commenters who have said it was too easy and some who said it was too hard. If we went with one of the previous versions most of our commenters probably would have exclusively said the latter, so I'm glad we put a focus on ensuring everyone could grasp the mechanics rather than creating an intense and demanding challenge.