Admittedly I haven't tried this out - but it looks to me like there's a possibility of a saveable but unwinnable game state in the armoury, if the player has not previously collected the ice spray.
It looks like it's possible to get the purple gem from the laboratory without collecting the ice spray, and completely clear the fortress basement and fortress mine without the ice spray. There are features in the library that can't be accessed without the ice spray - but none of these are essential for the main quest. So I think the first map that the player will come to, where it's essential to have the ice spray to progress, is the armoury.
They don't need to use the ice spray to cross the slime pit from 20224:8896 to 19776:8896, though - because they can use the slime potion for that. They might even be able to use the slime potion to cross the pit from 21472:12736 to 21024:12736, by using the sword to defeat the mouth stalks, and then shooting arrows from the right of the pit to kill any dragonflies and armadilloes there might be on the left of the pit, before using the slime potion, crossing over the pit as a slime, flicking the switch to turn the light beam on and crossing back before the 30 seconds is up. Once the player has flicked this switch, they can then get the rope.
If the player carries on to defeat the treadmill-operated centurion, and uses the slime potion to cross the pit that the centurion falls into from 25408:6656 to 25696:6656, they will reach a save point at approximately 26400:6592. However, if they save their game here without having previously collected the ice spray, then the saved game will be unwinnable, regardless of whether or not they have the rope.
Removing the save point at 26400:6592 by itself wouldn't solve the issue, because if the player has got the rope, they can still progress on to the awesome foursome battle area, and use the save point just before it. However, you could prevent the player from getting the rope without the ice spray by surrounding the switch at 20352:12672 with weak wall blocks, that the player needs to use the pickaxe to break. So I think the combination of removing the save point, plus putting a weak wall around the switch, would solve the problem.
Alternatively, I think you could solve the issue by removing the horizontal lifts from above the pit between 22880:7680 and 23488:7680, thereby forcing the player to use either the slime potion or the ice spray to cross this pit. If the player uses the slime potion to cross this pit, then they won't be able to save their game without either backtracking across the pit, or crossing the pit that the golden centurion falls into - which the player won't be able to do unless they have the ice spray. If you think this makes the solution to the game too obscure, then perhaps you could add a cut-scene action point just before the pit at 22880:7680, to warn that the player might not be able to get back if they use the slime potion.
I haven't tested any of this though. But thanks for the brilliant game.