2D gameplay with 3D graphics is fine.
The graphics are definitely ugly for a game from the 2012, but still had 176k plays!
Ugly graphics and over 150.000 downloads both on GameJolt and Play Store
There must be something related to either gameplay, or the fact people thinks there is a bitcoin miner/malware inside my game i think.
It's likely not one thing that drives away all your customers. Likely some segment is driven away by bad graphics, another segment by bad gameplay (you can sorta detect this by your user metrics - did they play for ten minutes and never return?), another segment by never having heard of the game in the first place.
For me, I see this and it drives me away:
Since you want feedback, I take a second look and see the graphics actually aren't all that bad, but it has some garrish issues that prevent me from seeing that on my first glance - and most players will probably only give you that glance.
If you look at the picture as a whole, it is an vibrant lime-green burning my eyes like acid. The 3D modelling isn't bad, but the brightness of the yellow-green is pretty intense. I think even digitally altering this one image may get people in-game.
The problem is, a customer's eyes has to adjust to the garishness of the image before seeing that it doesn't look bad, but they aren't going to wait.
The second problem is, your eyes are already adjusted to it, so it's hard for you to see it. Try setting it as your desktop background, so you see it at unexpected times when your mind isn't prepared for it.
I think the game also suffers from a lack of shading. The bitcoin is flat, the blue arrow is flat, the fences don't seem to cast shadows.
Also your text is hard to read. Where it says "the bittles", for some reason the first word is in all lowercase, and the second word is in all uppercase. The first word is in one font, the second in another font. The first word is near invisible, and the second has a bunch of dots making it hard to read.
Honestly, I couldn't see the first word at all, and the second word at a glance looks like it says BITCHES rather than BITLES.
Further, "Bitles" is actually spelled wrong. I know it's a word you made up for your game, but it's actually spelled with two T's, unless you're localizing into French. English has rules and a certain feel to it, so even made-up words need to follow that.
I don't know the specific rules involved here, but intuitively:
"Bitles" reads as "Bit less"
"Bittles" reads as "Bit tolls" (i.e. "a small bit")
Don't get discouraged. You've completed a game, which is incredible!
The problem now is, your game needs to be polished and refined.
I don't know the source of the quote, but "Polish is everything you do to improve your work AFTER you thought you were finished."
Or you can roll the knowledge gained into your next project... but to do that, you have to actually understand what's wrong about this project, or you might just repeat the same mistakes.
Oh, and I haven't played your game, I just saw that single image I re-posted in this post.