Hodl The Coin is still in early beta, and as you correctly pointed out there is currently no change in difficulty level, meaning it is effectively a game of endurance and fatigue for leaderboard spots. The developers do intend to add things like higher difficulty modes, and possibly competition/prize integration.

I got started on the Flappy craze with Floppy Tickets which has gone through several iterations. The original version also had no change in difficulty, and Hodl The Coin currently plays more closely to the original Floppy than any later versions or even Flappy. If you search on Youtube you can find videos of players scoring in the thousands of tickets on original Floppy machines. Subsequent versions of Floppy increased the difficulty; one version had the gap between pipes gradually getting smaller and smaller throughout the game. The most current version has moving pipes that come into play once a player reaches the 100th pipe in a single game. I'd expect Hodl to offer something similar when the devs get around to implementing higher difficulty modes.

As far as how I felt, it was much easier to play Hodl, as I only had to worry about clicking a mouse button with one finger, as opposed to a Floppy machine where I have to use my whole palm to press, and sometimes even quickly mash, a large button. As far as repetitiveness goes, I guess I'm conditioned to tolerate it better than most other people thanks to all the time that I spend in the casinos playing video poker and slots.

I'll certainly consider being a tester for any new games -- just let me know when they come up, and I'll take a look and see whether or not I want to do a particular game.