You should definitely make it free for a while or even give out coupons. In the meawhile checkout https://www.reddit.com/r/playmygame/

Thank you, but the people on r/playmygame are just interested in free games and won't spend money on it anyway. I already tried to promote it there, it didn't help at all.

the problem is discovery brother! and there simply doesn't exist a place where gamers can ably discover you and in turn you find gamers of intent. Check out playworthy.io, its a user generated discovery platform. You could try your luck there. Have you tried reaching out to any influencers?