Who Wants to Be Who Wants to Be a Millionaire?

In 1999, things were looking bleak for the American TV Game Show genre. There were no prime-time network game shows, and the only shows around were holdovers from the 1970s and 1980s — The Price Is Right, Whoopi Goldberg's Hollywood Squares revival, the latest (and lamest) Match Game revival, and evergreens Wheel of Fortune and Jeopardy!.

Then ABC decided to try out an American version of a British show called Who Wants to Be a Millionaire?, and quicker than you could say "A Mark Goodson/Bill Todman Production", a new era in the old format was born.

Of course, when a show is successful, everybody else wants to Follow the Leader. Many games, specifically in primetime, shamelessly borrowed many of the elements that made Millionaire so unique and successful.

Shows that attempt to mirror Millionaire commonly have the following features:

A large top prize, usually $1,000,000.
A single contestant or team competing against "the house", as opposed multiple contestants competing against each other.
A "money ladder" or "money tree", in which each right answer moves you up to a higher amount.
Multiple-choice questions that tend to get more obscure and trivial as you progress, practically making the advertised jackpot Unwinnable by Design unless you happened to be an expert on the final question.
Losing all of your money if you answer wrong, unless certain levels of the money ladder are "safe havens" where you're guaranteed to win at least that amount.
Lifelines.
Gratuitous Padding, such as pauses before the reveal of the answers (sometimes spilling over into commercial breaks).
Dark theater-in-the-round sets adorned with complex lighting setups.
Foreboding music, oftentimes involving a Heartbeat Soundtrack.
Giving away the outcomes of upcoming games, in the hope that it'll entice people to watch.

Don't add examples to this page unless they clearly were influenced by WWTBAM. The mere presence of Lifelines or a $1,000,000+ prize does not automatically mean it's a Millionaire clone. Premiering after Millionaire doesn't instantly make it comparable to the show. We're looking for shows that tried to emulate the whole package — game format, presentation, etc.

Shows that tried to follow in Regis Philbin's footsteps:

1 vs. 100: A multiple-choice quiz against 100 Mob members for a $1,000,000 prize. In the US version, the resemblance was only made stronger in season 2 with the addition of a money ladder, plus its original question writing style was thrown right out the window in favor of the same style of writing from Millionaire.
Are You Smarter Than a 5th Grader?: A million-dollar quiz where a single player answers up to 11 questions from grade school textbooks, using Lifelines known as "Cheats" to gain answers from an appropriately-aged classmate.
The Cube: WWTBAM with tasks instead of questions.
Don't Forget the Lyrics: A carbon copy of Fifth Grader, using song lyrics as opposed to academia.
Duel: Millionaire meets World Series Of Poker. Players compete for a growing jackpot by defeating opponents in a multiple-choice quiz. The second season enhanced the comparison even further by awarding the jackpot to winners of five consecutive matches. Defeated champs who had won at least three matches had their winnings cut in half; otherwise, it was All or Nothing.
Downfall: Same premise of climbing the money ladder up to $1,000,000, with the added risk of throwing additional prizes off the side of a building.
Greed: One of the first (and most blatant) imitations. FOX ads gleefully bragged that you could win two million dollars on its show.
It's Your Chance of a Lifetime: The only differences between this show and its forefather were: an opening question to pay off a credit card bill, only nine questions in your stack instead of 15, and wagering on each question to determine its value. Aside from that, probably the closest imitator of the bunch.
Million Dollar Mind Game: An American version of the Russian game show What When Where, six contestants work as a team to answer increasingly complex questions with each player taking a turn as team captain. The main difference from other shows on here is that visual aids are used for many of the questions, up to three incorrect answers are allowed and the contestants vote on whether they want to keep playing the game or walk away after each question. It's worth noting that the original Russian game have neither lifelines nor money tree. It has a lot of padding though.
Million Dollar Money Drop: Inverts the trope by giving the team the million dollars right at the start, but forcing them to keep it by placing the money on answers to multiple-choice questions, and losing money placed on wrong answers.
Minute to Win It: Millionaire money ladder meets Beat the Clock-type stunt show, with bonus heavily-caffeinated Guy Fieri. Initial episodes played it straight, but later episodes loosened up the feel of the show, and even added lifelines.
Paranoia: A single studio contestant tries to win money while three other contestants playing via satellite and scores of online players tried to siphon the money away.
Million-Dollar Password: Tried to slap a money ladder onto the classic Password game while overhauling the front end to be rapid-fire.
Power Of 10: Players answered survey questions to win up to ten million dollars.
21: The 2000 revival of the rigged quiz had a cumulative money-ladder that ultimately awarded a million dollars for a player's seventh consecutive win, and a Lifeline in the form of a family member being brought on stage to help on one question. All of the questions were multiple choice (although for the most difficult questions, players would have to pick two correct answers out of five choices).
The Weakest Link: The American version had the usual "money ladder" format with only minor changes from the original version of the show.
Winning Lines: Originally produced by the same people behind Millionaire, it's U.S. version for CBS was adjusted to compete against it/ The relatively minor changes included the addition of a $1,000,000 top prize to its Bonus Round, along with additional Lifelines and a way to lose.
Who's Still Standing?: U.S. version of the Israeli show, there's one main challenger who challenges a circle of other contestants in duels over trivia. Most of the hallmarks are there. However, unlike the other shows listed, this one also rips off the new "shuffle" format the syndicated version of Millionaire uses; each contestant is worth between $1,000 and $20,000, and the final 3 contestants are worth $250,000, $500,000, and $1,000,000.