That's a really great game you made! Micromanaging your "towers" in this tower defense was a lot of fun. Every jump in difficulty meant I had to scramble to optimize my damage output by tactically moving my space armada; every slow round left me with something to do. There was a lot of variation in space ships to upgrade and explore and every one felt like it had a purpose (except maybe the purple replication-blocking one - I didn't feel its impact a lot), which kept the game fresh until the end. A+ gameplay, really.
As for critique, I really only have one pain point. As the game went on, it was increasingly tedious to find space ships you hadn't upgraded yet. There wasn't a visual difference (at least I didn't notice one), so I had to either remember which space ship had which upgrades or click myself through every one of them. I understand that this is a jam game and you are a solo dev and it's an ultimately small nuisance, but it's something you may want to consider if you choose to expand on this game later.
The sprites and special effects were simple, but pretty. The enemy block blobs were pleasantly colorful and watching it multiply felt really satisfying. Shame I had to blow it up. Visually, everything stayed clear despite the chaos of the rapidly multiplying blob of blocks and space lasers. The sound effects were fitting and the music was fine for the most part, but descended into unpleasant noise at some points.
It would have been nice to see more of the theme in the game - the "malfunction" aspect is largely relegated to the story, but doesn't show in the visuals or the gameplay.
All in all, this was a very enjoyable entry.