I think the gameplay loop could use some variety. Once you get some upgrades, it essentially boils down to applying the same strategy for the same enemies over and over again, eventually making gameplay not engaging after like 20 waves. I'm thinking the easiest way to work around this would be to add one or two extra types of enemies, for instance, ones that can predict your movement and shoot in that rough direction or something.
Other than that, visually it looks very nice and controlling the ship feels pretty good - you've definitely spent a lot of time on game juiciness and it shows. However, you get minus points for square grid in hex-based jam LOL.