A gauntlet tournament is typically where you have a set of challenges (score, mode, etc) on different games and you have to complete them as quickly as possible. Another way I have seen them run is there is a set amount of time and you couldn't possibly accomplish everything so you try to strategize and do as much as you can.

The latter format has the very nice advantage of having a defined time schedule. Open-ended tournament play is always tough from a scheduling perspective.

The cool thing about a guantlet tournament is they usually force you to think differently about the game and they also don't require special set up of the games. You don't have to re-level, (usually) don't have to modify rules/software, etc.