Basically, it's just an improve version of crash game. It's a fun game if you've experienced trading shitcoins before as what LM said.
It doesn't attract many players mainly because of its dull animation.
First of all, the HODL game is just a moderated version of crash game. I won't address it as an improved version. And it is failing to attract the bettors for it's system. Gamblers usually like to see the flow of the profits after placing a bet. They have made it different by doing retouch with trading vibes. Crash is one of the most played and popular games in all other casinos. At BetHog, no one is playing the HODL game for the different system. Personally, I didn't like it as well.
I tried to open this game for 10 minutes and there is no player who play this game. You are right, maybe players (especially those who love crash) do not like how this game looks like at bethog. I know. I guess bethog want to make it a bit different to most other crash game by combine it with trading chart but it seems that it does not give good impression from crash lovers. I am not a fan of crash game but if I have to play crash, I'll choose crash with the common UI/animation.