Damn, Utah's artwork never ceases to amaze. This is easily the most polished looking game in the jam and it's clear he's the reason.
The first couple minutes of this game I thought it was going to be too simple to be enjoyable, but the mechanics are added in nice and slow and ramp up into a pretty fleshed out experience. The added mechanics were a mixed bag. I never once fell for the decoy vehicles until the last level, and the drone sequences felt a little tacked on, but I also really liked that the vehicle stopped for the drone sequence - it gives the player a bit of time to catch their breath in a game that otherwise doesn't stop moving for a second.
The random all-ATV level, surprise boss at the end, or crushing the robots with heavy cannons were neat ideas, I would have liked to see more stuff like that. Perhaps having a mismatch between the vehicles and the cannons and forcing the player to equip vehicles with weapons below their weight class would have been interesting, but as-is I mostly found myself only doing this toward the end of levels if I made some pretty serious mistakes earlier on.
For the fights themselves, the Cassandra-bot (I'm calling it that because that's totally what it is) is a bit simplistic; shoot out its eyes and you're done. Having it regenerate mid-battle would keep the player more focused. Also, having the drones fly in multiple directions would allow the player to purposefully let some of them explode behind enemy lines. Or, drones could explode upon death, making it so that you could shoot them down only while they're over enemy lines? There are a lot of ideas that could have been explored here that weren't.
All in all, there's a lot going on here and even more that could have been added. It's unfortunate that the bulk of the difficulty increase comes from increased speed, as it seems like the most bland way to increase the challenge. It can also make this game a bit overstimulating, as you're watching very bright colors moving across the screen quickly while not taking your eyes away for even a fraction of a second.
I'm curious why you didn't make this a rhythm game. You've been doing this for 20+ years so I KNOW the thought crossed your mind.
My last note would be that it's interesting to see how this performs with Ruffle. Some of the later fights can take a pretty serious toll on the framerate, but as the battlefield clears up it's usually not much of an issue at all. I can't help wonder if this game is the byproduct of a stress test that you decided to flesh out into a full game, considering how easy it is to arbitrarily add in objects.
Btw, you forgot to tag this with "flash-forward-jam"