Supposing you enter the WSOP main event and someone says you're going to be dealt KK every hand. And everyone at the table *knows* you have KK every hand. What's your strategy? (in the early stages, where you can't unexploitably shove every hand).

mostly sit back until antes kick in, then open shove every hand

Raise 10% or 15% of your stack and fold to a 3 bet.

This is wrong. If you have chips left to bet once the flop comes down, you are somewhat stuck unless you have the top set giving you the nuts, when you jam. Villain will never make a mistake: he won't call a bet unless it's correct via either odds or being ahead already. You simply cannot bet.

You'll have to shove every hand you play preflop. It's just a matter of how long until you run into aces. You should have enough stolen chips to survive (since the only hand that other players can play is AA and whatever bluffing combos they decide to balance with.

You can't shove all the time when someone bets in front of you. That can't be equilibrium since in that case they would never bluff and always have AA or possibly KK. I think you can never shove when someone has bet in front of you since they will only be calling with AA or KK.

I would!

Anytime someone uses the word 'never' in poker, you have exploitability.

I was responding to "You'll have to shove every hand you play preflop...". If KK shoves every hand then he is playing a fixed strategy and won't be exploiting someone who never bluffs. He is being exploited by them.

If I can't unexploitably shove, I'll fold. End of story.
If I can:
I haven't done the math but you could probably, cEV-wise, start open jamming SB on level 1 - but you'll definitely want to let that go and blind down to reduce variance to the absolute minimum, because your edge will begin to get ridiculous when stacks become shorter. I suppose you should even sit-out (or constantly time down) the first couple levels to maximize $EV.
PS:

Here is the cash game math assuming 100bb stacks. Actually, shoving every hand is –EV except for one or two opponents.

Assume 100bb stacks, you shove every hand and villains never bluff.

We’ll first consider heads up. Villain only plays aces and KK. In 200 hands, he gets one ace and calls your shove of 100bb. You lose 80% of the time so your EV in this case is 0.2*100 - 0.8*100 = -60bb, ignoring the blinds. For the other 199 hands, you win 0.75bb on average, or a total of about 150bb, a clear win for shoving every time. (Note I did some approximations, but exact won’t differ by very much. For example, I left out the very small chance villain also has KK.)

Now for a full ring game with 8 opponents, the chance one or two opponents have an ace is about 4%. Then in 200 hands, 8 times you will be facing an ace so your overall EV is 8 *-60 + 192*0.75 = -480 + 144 = -336.

You can show that with 3 or more opponents, shoving KK every time is a losing strategy if villains never bluff and stacks are 100bb. With lower stacks, always shoving KK gets less attractive. Since OP’s question was for early in the tournament, this cash game analysis could well serve as there may be no ante and ICM factors are not in play.

:S

just wait til you get a smaller stack, the real question would be in a CG, in tourney you could just wait til you have 20BB and never make a mistake

9 handed you aren't winning 0.75bb a hand, you are winning 1.33bb a hand. Which is +256bb over 192 times. With a 20%bb ante you are winning 3.13bb a hand, or +601bb over 192 times.

So the first comment was mostly correct. Although I'm guessing (not really sure how much the 4% figure actually goes down with folds though) if the hand starts out 9 handed there don't need to be a lot of folds in front of you for a shove to be +EV.

1.33? since when is the SB 1/3 the BB?

Odds of running into Aces with KK against # of opponents (wikipedia.org):
Against 1 0.0049
Against 2 0.0098
Against 3 0.0147
Against 4 0.0196
Against 5 0.0244
Against 6 0.0293
Against 7 0.0342
Against 8 0.0391
Against 9 0.0439

should be easily to calculate when shoving is +cEV...
But tournaments are still about survival besides accumulating chips, so it's not necessary to take all the small +cEV spots, just the big ones, just shoving SB BTN and CO for example would already be so massively +EV that you don't need to risk shoving from the other spots...

should be the easiest ME victory of all time btw

Sit out until blinds, antes if applicable, get to about 3% + of your stack, and / or you're in position against small (relative to you) stacks? Should be mathematically solvable, it's an optimal blind taking strategy right?