Nice game.

But I think you need to work on better "opposites". E.g, "as of now" and "long ago" don't really seem to be opposite. Instead, maybe they're complex conjugates of each other. I.e, they have similarities along one axis (time frame) and differences along another. But I wouldn't consider those two to be opposite one another. Word2vec with a consine similarity closer to -1 might be better than what you're using now.

the older generation of vectors, like word2vec, compress to one sense of a word, but even if we ignore polysemy, opposites have a lot in common. So for any antonym pair, they would not be minus-1, they would be actually pretty close.

The big challenge is when we go beyond antonyms with clear scales like heat, speed, size. To me "as of now" is recent, and therefore opposite to "old". I would like a word other than "opposite" or "antonym" or "contrast" that captures a wider range.