Hi thanks for the feedback!
ESR is meant to be a pretty hardcore game and mastering the tactics is the crux of surviving very long. Though with only a week to make it it there wasn't much time to playtest and tune the difficulty level so this is something I'll be looking at in future development.
The problem with a cancel/undo option is the player could take a few steps to reveal more of the map, get information (like enemy positions) and undo to get all their move back with the bonus information.
But I do know what you mean - it's very easy to make little mistakes! I've made them plenty while playtesting.
What I could do is add a "path planning" step where you plan out your movement route then you can press a button to confirm that route so you get a second chance to validate it's what you want before committing. I could also add validation to attacking, so you can't attack unless there's something to hit in the target area, as I've messed up and wasted shots a few times.