Cool to see a Pico-8 game not really sure about Pico-8s capabilities and restrictions but it seems like you did a good job.
The gameplay is pretty basic and fun the base fire rate feels like it's pretty slow which forces me to be a little more considerate about my shots instead of just holding down the Z button. And being able to run into enemies gives me some cool options as well. Also it's super weird that you start the game with X but don't fire with X that threw me off.
I actually really like the upgrades here the shoot up one is just standard fire rate increase and the slow down one is helpful. Usually I am not a fan of the increased movement speed upgrade that a lot of people have in their SHMUPs but here I like it a lot more cause you can crash into enemies. I wish there was an indicator for what upgrade was dropping so you could plan around it a little more but I think it's implementation was mostly good.
The visuals that are here are good even though there's obviously stuff like no background and no death effects. The sounds here are all solid it's just missing music. Overall I liked the presentation something about Pico-8 and it's colors are so appealing.
It's a simple high score shooter but I enjoyed it so thanks for submitting!