Some thoughts (and these are based on the demo, so it could be different with the steam version and I just don't know):
I feel like flagging should be able to be done from afar. It's very tedious to have to go up to each rock to do it.
I think the game might benefit from being able to zoom out, but that's just me.
I think there should be a save system if the map is truly infinite. What if I want to call it a day and come back later?
I played for an hour and while I could see the benefit of the rail system, I kept thinking (ok, but what am I working toward or what is my reward?) and I never found it. Other incremental games either give you some story or something that feels rewarding for having made it further (a scoreboard where you can track yourself, some wacky effects, fun power ups, etc.) , but from what I could tell, this wasn't giving that sort of reward.
And I agree with folks complaning about the legibility of some numbers like 4 and maybe 6. I wasn't sure what number I was seeing for a few of them.