Wowie is this game hard! I enjoyed it a lot though! I get why you used the gridlocked movement, it allows to avoid people underestimating their moves and die. Though the game is very fair (it does not feel like the game cheats to get you to die), I have suggestions for the death mechanic:
1) Make the screen clear when the player dies
2) Maybe add a "you died here" marker on placements where the player died? I feel this would add value to each run.
This could make the game more friendly without tuning down the difficulty. I also feel that the second option gives the player a good mental map of where he is if he dies a lot hehe.