So.
I'm assuming this is some sort of game programming class or something for high school as opposed to college. If it is a game programming class and it is optional, I'd get out if possible: so much of it is going to be visual, up to and including making/getting/working with graphical resources; your time would be better spent online or in a more general programming class.
That said, BGT is probably not going to work. This is not about complexity-ironically, BGT is probably more complex than unity, at least if you're trying to do the same things that unity does. A lot of the draw of unity is that you can literally edit the game while playing it, or at least seeing how it will look to a player: it gives you what is basically visual studio on steroids, and you build really, really complex maps by using what is basically paint on steroids. "When the player is this close to this object" is all drag/drop/click the menus, and then "execute this script" is finally, at long last, coding. Walking is handled. Collision is handled. Physics? Handled again. At least half of unity is about the artist, not the programmer, and consequently Unity lets the artist do a lot of what people think programmers do.
So basically, without any programming at all, you get a truly tremendous amount of stuff. Epic. Give me something equivalent for audiogames, and I can give you a new audiogame literally as fast as I can figure out level design.
BGT does nothing like this. BGT doesn't even have graphics, not unless something happened while I wasn't looking. The ability of your teacher to grade or even appreciate a project done in BGT is limited, possibly nonexistent. If you wanted to duplicate unity in BGT, assuming someone gave you graphics, you'd be looking at 5-10 man-years, linear algebra, trigonometry, possibly basic calculus. Most of the systems for the sighted are this way.
There are literally two alternate universes here. The universe of blind gamers is so far from the universe of what Unity does that, unless you've played a game for the sighted, you are probably not able to appreciate the differences.
If you have a sighted partner, looking at one of the code-based engines will do the trick, but you won't be able to go nearly as fast as your sighted peers because you'll be implementing stuff they get for free: as an example, collision detection, a scripting system, etc. The stuff you have to deal with to make a Unity-level game without Unity includes all the aforementioned maths (yes, even if you have libraries. Understanding those libraries requires it). There is no accessible alternative: even things like Panda3D don't come close in the sense that they're still slower, at least not for a blind person-any of these frameworks may have comparable tools, but the tools have the same exact challenge as Unity. I surveyed all of the RAD options for games for the sighted, especially MMO-style games. They are all basically Unity by another name, and most of them don't even have accessible text editing.
All alternatives in this thread are like comparing spaceships and the internet. Both are very technological, great examples of their type, wow humans have come a long way. But the internet and spaceships have nothing in common. The world of Unity and alternatives to Unity is completely separate from the world of <3 or 4 packages and purely programming>, in much the same way that these don't even compare.
Sorry to be the bearer of bad news, but there is no purely programming approach that is even comparable. No matter what you do, you're basically going to need a different syllabus or to work in a team and take the back seat on everything. To do the same as your classmates, you will have to deal with at least 10 times the complexity and probably 100 times the code. The games you will make due to your visual impairment will not be able to incorporate the third dimension, at least not with the time you have (I'm assuming the standard semester). Even if you had more, literally the only example that comes close is Audioquake.
As for making graphical games as a blind person in general? Not without sighted help or remaining vision. CAE is the only one who is trying to my knowledge, and I don't think he's managed it yet. I also think he's having help (CAE, correct me on this if you've somehow managed to do it without).
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