I'm sorry to hear that. I'm glad you managed to progress further through. I'm thinkin of just making you have unlimited checkpoints. You can see on the update agenda and the main menu I plan to add challenges, so I may just make no checkpoints a challenge for people who've played the game a lot and wanna test their abilities more. Or for a steam achievement when the full game releases.
The point of the limited checkpoints is to force people to be aware of them, so they need to consciously space them out. However, I think the level at the moment is just a bit too hard for that to be reasonable to new audiences. This is a foddian game, so it is meant to have a small rage element, but it's also a speedrun game, so it should be completable within a reasonable amount of time. We'll see.
But, assuming you only got to the first level in the outside area, that means you only actually have 5 screens to go, including the one that's just you standing there, the ending one. And being able to finish the game is a couple hours is a pretty good first completion time. So I'll leave it at 20 for now. If you'd still like to play further and beat the game, let me know after a few more attempts if it's just truly too difficult to get to that point without using all your checkpoints.
I'll look into the bug as well. I've had a few times where I glitched into the ground chunks while I was sprinting and dashing around like crazy actively trying to break it, but it wasn't even remotely repeatable. This bug will probably take a bit longer to fix, since I need to identify the problem basically through trial and error. For now if it only happened to you once in 40 minutes or longer I can leave it allow to focus on more important updates. But let me know if it starts happening more frequently.
Thank you for playing! This has been extremely beneficial feedback. ^^