I released a version making the tutorial easier yesterday. First section slightly easier, second section significantly easier and there's a full heal in between.
The threat area of the new character being red instead of orange feels really unlikely, that's never happened before. (If you try the game again and see it, maybe send me a picture. And tell me if you otherwise have difficulty telling apart the colors.) The colors change a bit when characters have no reactions left, but they're still very different to my eyes.
You right click (or click outside the board) to deselect. The tutorial says to right click, but I can see why you'd miss it, since it's at the end of a kinda long textbox that you have to close to keep playing. I got a few ideas for how to make that harder to miss + make it work on platforms that don't have a right click key.
Checkpoint system is on my radar and I think I can do some neat things with it for the second level. It's just something that can easily end up pretty fragile / with a lot of stuff I have to manually check, so it'll take a bit of work.