So I was lying in bed last night, thinking about zombie apocalypses (or is it apocali?

) as you do, and have come up with a cool concept for my zombie survivor game. Though I haven't decided on the main goal yet, I want to have set 'events' which mark levels in the game. By events I mean key stages in an apocalypse where life takes a dramatic turn. So far I have it as follows ...
Stage 1 - Outbreak
The player takes control of his character during the initial stages of the outbreak. This will also serve as a tutorial level. Essentially there is a simple cut scene of the player sprinting towards his house or a building of some description, being chased by the undead (there will be fast and slow zombies in my game). As he runs, other innocent civilians are taken down left and right.
When he gets to the house he slams the door behind him and then the player has control. The tutorial will direct him to barricade etc. and essentially take him through the controls and features of the game from the safety of the house.
The mission in this level is just to survive the initial outbreak and possibly to attempt to save some neighbours. Not thought it through yet. The player will learn about fatigue and hunger and how to keep their character going and how to sleep safely etc.
Stage 2 - Supplies
At some point, the game will inform the player he needs food. This stage will encourage the player to venture outside more in search for food, weapons, medical supplies etc.
Stage 3 - Power Off
At some point, and without warning, power is going to go off PERMANENTLY. So up until this point, the player will have the tele on (simple background looped broadcast), lighting will work (to some extent - not sure of engine limitations yet), and cooking facilities will work. Suddenly it will all go dead, forever. At this point the player will need to find batteries and work out how to cook food without a cooker.
Stage 4 - Water off
Next the water will dry up. Up until this point, the player will only have to go to their tap for hydration. Now the only source of water will be from items scavenged. I'm toying with the idea of having a simple bit of function where items flagged as "liquid container" can fill up if left outside when its raining, though I'm not sure if I'm going to do rain yet.
Stage 5 - Winter
Next, I want winter to close in. How I'll do this will probably be a few tile/map sets. One for getting chilly/autumn like, and one where the player wakes up and it's snowing. I will introduce a warmth stat, which if it drops too low, rapidly increases fatigue etc. The key here will be to find the best clothing items and make use of fires a lot.
Stage 6 - Sickness
Surviving the harsh winter brings on illness. This will basically slow the player down massively and make everything 10 times more difficult (fatigue etc). The idea here will be to use maximum stealth to survive and try and find medical supplies. The player will be largely incapable of running away or hand to hand, so it'll be a whole new challenge.
Stage 7 - Escape
I think the game will end with the player either being rescued, or escaping to a safe haven. I think a side quest where the player gets a CB radio working using old car batteries could ultimately be the way to win the game. I might not even make this obvious. I could give them the facility to turn this radio on and call for help (use radio function), and nobody ever answers, but if they use it every day, eventually someone will. At this point, a chopper comes to save them. Alternative endings could be provided.
Anyway, that's the basic outline of my idea. I want key stages or events to keep the survival challenge real. I'm really looking forward to the power-off one. I think that'll be awesome. It'll definitely happen at night.
My question is, does anyone have any ideas for what would be key steps in this journey? Anything missing from this survival tale?