i feel like, if i were to try to make something out of these pieces, there'd need to be some randomness to the levels. i've never felt ready to approach random generation, but maybe it'd be enough to just change around where the goal is located, and the enemy placement.

i feel that the timer would need to be the biggest threat on a player's mind. as soon as you enter the level, the timer starts, and you have to be back to the entrance before it runs out, or else... the entire campaign ends?
maybe dying via running out of health would have a smaller but still major punishment. like "just" removing a ton of your resources and items.