Win Your Freedom

To any victim of long-term incarceration, being set free from it is the ultimate MacGuffin. Of course, it won't come cheap, but when the alternative is to rot and die in captivity, they'll gladly risk their life on whatever No OSHA Compliance Death Course is required of them to get it.

The favorite motivational carrot of Boxed Crooks and Condemned Contestants, since they're already locked away, but the threat of incarceration can be used preemptively so long as the victim is already powerless to resist. Any kind of Deadly Game or Gladiator Games is likely to have this as the prize since most people wouldn't risk their life without an appropriately large reward. Likewise, the Most Dangerous Game has life as the reward.

One common variant would be when its the victims friend or family member whose freedom they're trying to win. Shows great dedication when the victim could just turn and walk away and leave them to their fate.

Since the kind of people who are locked up are typically not someone the captors want to let out, not to mention that doing so would mean losing their services, it's common for them to sabotage the victims attempts at fulfilling the terms of the agreement, just changing them as needed, or lying and killing them. If anyone asks, the previous "winners" were Released to Elsewhere. Just about every Evil Overlord does it at some point, typically making the challenge Unwinnable by Design. Of course the hero goes Beyond the Impossible and wins, only to realize he was being baited and breaks free instead.

Forced Prize Fight and Death Course often go hand in hand with this. Practically every Closed Circle adventure game ever.

Film

 * Escape from New York/Escape From L.A.''
 * The Running Man
 * Death Race
 * Gamer
 * Punishment Park
 * Gladiator, although Commadus isn't keen on it happening.
 * Megara in Disney's Hercules would regain her soul from Hades if she helped with his scheme. Surprisingly, Hades held up his end of the bargain.
 * The Rock..

Literature

 * The Stainless Steel Rat
 * Between The Winter Queen and The Turkish Gambit, Erast Fandorin fights in the Russo-Turkish War and is taken as POW by the local governor. However, when he accidentally discovers information crucial to the Russian army, he wins his freedom in a game of checkers (because he is Born Lucky and never loses bets, even when they don't actually involve games of chance) and leaves.
 * AI Programmer Sofia Mendes has to book enough programming jobs to be released from her "intellectual prostitution" by her broker in The Sparrow.
 * In Mrs. Frisby and the Rats of NIMH, the (apparent) reward which lures the captive rats through their training-maze at the National Institutes of Mental Health is an open passage to the outdoors. It always slams shut before they can escape.

Live Action TV

 * The premise of Alias Smith and Jones. The reformed outlaw heroes will get a pardon once they convince the governor that their Heel Face Turn is real.
 * On My Name Is Earl when Earl was incarcerated the warden kept giving him "time off" coupons for various good deeds, but when Earl earned enough of them to get out the warden reneged.
 * Sawyer in Lost ironically bypassed most of a six year sentence by agreeing to con an inmate into revealing the location of a large sum of money he stole.
 * A prisoner in Day Break was let out temporarily so that he could.

Theater

 * A Funny Thing Happened on the Way to the Forum: Almost everything Pseudolus does is because of this trope.

All the Tropes How to Guides
"I will not agree to let the heroes go free if they win a rigged contest, even though my advisors assure me it is impossible for them to win."
 * The Evil Overlord actually has this on his List.

Video Games

 * Radiant Historia - Stocke has to do this by trampling through a set of gladiators.
 * Shin Megami Tensei Nocturne - Wanna prove your "innocence" in front of the Mantra Army Court? Get ready to punch out Thor.

Web Comics
"Alien Captor: I plan to study you by giving you everything you desire and watching your reactions. Scott: Fine by me. Alien Captor: You'll have everything but freedom. Scott: I've had freedom. I'd like to try having the things I desire for a change."
 * Beyond Temptation: Demons who abandoned Lucifer during his Rage Against the Heavens are imprisoned in boxes. Their only chance for freedom is to tempt enough souls.
 * Subverted in this very funny Basic Instructions comic:

"Cypress: "I know critics will say that our new show is cruel and unusual, but we're doing everyone a favor here! Death row is far more cruel. Half our players haven't seen starlight in the past ten years! We're following every law and code on the books, and if anyone else has a problem, I have four words...speak with my lawyer." Lawyer: (very rapidly) "By asking me a question, you hereby acknowledge that any answer you recieve will be sufficient insomuch as that if you disagree with the answer, I am not obligated to provide you with a better one...""
 * So far, Last Res0rt looks like it's playing this straight, for the criminal contestants. They've all been offered their freedom, if they survive (and, one assumes, win) the games. Cypress Vaeo, one of the people behind the show's creation and their 'face', has this to say to critics:

Western Animation

 * Jonny Quest episode "Dragons of Ashida". Mad Scientist Dr. Ashida refuses to let the Quest team leave his island, but he promises to let them go if Race Bannon defeats his servant Sumi in a judo match.

Real Life

 * Historically Truth in Television. unusually skillful and loyal slaves have often been rewarded with freedom.
 * Also Roman gladiators to an extent, though not all of them were forced to become gladiators in the first place.
 * In a bizarrely literal example, those slaves who were allowed a peculium could usually buy their freedom, by actually purchasing themselves from their masters.
 * At the Battle of Lepanto the Galley Slave s in both the Turkish and Venetian fleets were offered their freedom if they behaved. The Venetians were actually given weapons and told to fight whereas the Turkish Galley Slave s were just told to row-perhaps because while the Venetians were convicts the Turkish rowers were kidnapped Christians and could hope to be welcomed back as war-heroes if they mutinied against their captors and thus could not be given arms.
 * The story goes that the early 20th Century folk musician Huddie Ledbetter, aka Leadbelly, secured his release after serving 7 years of a maximum 35 year bid for murder by writing and performing a song for the Governor, then again after serving four years for attempted murder, having recorded songs for folklorists John and Alan Lomax. Although his musicianship probably helped, he was also a model prisoner and in both cases had served close to the minimum of each sentence.