Battle a horde of demons in the most effective way possible: projectile vomit! Eating food will refill your yak-o-meter, and change the way your yak behaves. But watch out, if you yak too much you will die of malnutrition. How long can you survive?
For much of my life I've suffered from chronic nausea, which often resulted in me throwing up my meals, and which was most intense around the time I developed Yak Attack. Additionally, because of my unusually fast metabolism, I have to eat as much as possible or I'll loose unhealthy amounts of weight. This lead to many doctor visits, blood tests, and dietary plans, none of which accomplished anything. My health problems - and the shame associated with them - exacerbated one another in a cycle: I would push myself to eat as much as I could, causing more nausea. Then I would get sick and throw it all up, causing more weight loss. This all lead to more visits to the doctor and more shame and stress. Immediately after one particularly embarrassing meal-loosing incident, I got on my computer and developed the majority of Yak Attack in a single sitting without any sort of plan.
I give this context to clarify the particular sort of humor within Yak Attack. While it's certainly silly and absurd, it's also self-mocking in a very dark way. For example, although exaggerated, the idea of shriveling up and dying of malnutrition felt very real to me at that time. We're all familiar with the idea of using humor to deal with tough situations, and that's exactly what Yak Attack was. I don't think I can fully communicate what it evokes for me, but it's the feeling of laughing at yourself for no reason while there are still tears all over your face and bits of lasagne stuck in your nasal cavities.
With all this said, Yak Attack is extremely simple and rather crude as a piece of game design. While it's the most conceptually interesting of the games I made in high school, it's still a game I made in high school. Yak Attack definitely won't impress anyone with its systems-level design, or the sophistication with which it explores its subject matter.