A poker tournament in which poker players are not permitted to rebuy once they have lost their chips.
A winner-take-all tournament with no re-buys. That is, a game in which play continues until one player has all the chips.
Any tournament format in which you cannot re-buy. A freezeout is a good format for heads-up pot-limit or no-limit play, since the amount at stake can be fixed in advance, and the competitors can use arbitrarily valued chips as in tournaments.