This game's "aliens steal cows" premise may be obvious, but it's also pretty creative for the shoot 'em up genre where the story tends to revolve around intergalactic wars and what have you (I'm still not entirely sure what the cows do, though; Nevermind, they fill the hyper gauge a little).
When you called the tutorial series this game is from "Making an Advanced Shmup", you weren't kidding when you said "advanced" – not only is this a more complex shooter than a Galaga-style thing mechanically, technically and visually, but "advanced" is also the skill level I assume this game was made for. Maybe I just don't have the reflexes and multitasking skills to observe and avoid all the bullets at once and pay attention to the "Last Life" warning and life counter. And is there a way to get extra lives beyond one-time checkpoint cassettes? (Also, it seems like the bullets sometimes cause visual lag.)
Good game, and a good-looking one for the PICO-8, too, but clearly not a game for newcomers and/or casual players.