If your perception is subject to failure, so to is the evidence, no matter how convincing. So yes, we act upon the assumption that reality exists. We both agree with this.
But that doesn't mean it is true. And all I'm saying is for this very narrow point of what I care most about, Descartes does have a point. I care more about my mind than my foot. I mean, maybe you can think of a better way to frame the argument because I doubt you even disagree. If you have a gun and you are forced to shoot yourself anywhere on your body, would you choose your foot or your brain?
The better counter to me would be to prove external value. Would I sacrifice myself for someone else? If I believe reality doesn't exist, the answer should presumably be no. If I believe reality does exist, the answer could be yes. Or alternatively, shooting myself in the foot suggests I believe in a causal relationship within reality towards shooting my brain and losing consciousness, which I shouldn't necessarily believe.
But even then, it's not that I disbelieve reality, it's just that I can't know for certain what's real outside my mind, so there's not really any contradiction between acting as if it is real and being uncertain if it is.
All this is doesn't matter anyway: the point is less you could be a brain in a vat, but rather if you were a brain in a vat, would you be any less you? I don't think so.
I have more evidence that the real world exists than I do that you are a thinking mind.
I have more evidence that I am a thinking mind than that I do that the real world exists. There's no point arguing this point it won't go anywhere.
I played it - and if it was truly only made by two people is quite impressive - but it's just alright. The world is very cool, and is structured around multiple levels of a tower each with their own language that you need to learn to progress. My main issue with the game is that the differences between these languages, and the puzzles built around them, aren't particularly interesting or deep or varied. There are a few gems, but overall it's much closer to a traditional adventure game than you might expect on first glance.
That said, the art and world design are very cool.
Edit: As an aside, it's worth noting that the Steam Reviews metric is a tad misleading in a similar way to Rotten Tomatoes, in that it only gauges ratio of positive reviews, over what those reviews are actually saying. A universal consensus of a game being a 7/10 (if we assume 7/10 is positive) will appear "better" than a game where 99% of people believe it is a 10/10, but 1% think it sucks. It's good at predicting whether you will like it, it is bad at predicting how much.