* Test your screenshots! Assume that 50% of the people in the market will never read your description. Right now, your screenshots communicate "Samurai game". Try a different direction, maybe one more Sudoku focused.[1] Test lots.
* Test your app icon. Test lots.
* You should have a purchase already. Review your monetization strategy. Most developers err on the side of under-monetizing their game, in the hopes that they won't "make players mad" or some other nonsense. Spoiler alert: you're wrong. Start your re-education here: http://www.edery.org/2012/08/your-first-f2p-game-where-you-w...
* Doing games is hard and a lot of what works in games is non-obvious. Be very skeptical of advice you get from anyone that hasn't done games.
* There is only one "tried and true" marketing channel - getting featured on the platform. Outside of that, you need to hustle hard to get your app featured in other places. You've reached out to "a few" sites and forums. Expand your reach to 10x as many sites and forums. Point to your past reviews as social proof for potential future reviews. No one site is going to bring in all the downloads - it's about building buzz and the snowball effect.
That's all I can think off the top of my head.
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[1] - No one can tell you what's going to work best. The only way to know is to test.