Starting thread to throw out some Seder ideas. Here goes:

Have a “prize wheel” or some other fun test of luck. Take turns spinning one person per part of the Haggadah. Possible outcomes are: “ask a question,” “read out loud,” “say dvar Torah,” “sing in random tune” etc...

Each person has two different sets of accessories: one representing slavery and the other freedom. Before each part of the Seder/Haggadah, put on the relevant accessories.

For Yachatz: Using poster board, draw, attach a bunch of matzahs split in half. On each half, place a clue for a number (math problem, trivia question, gematria, etc...) and based on the answers, decide which is the afikoman (larger number value)

For Yachatz: On poster board, draw a bunch of matzahs split in half. Place a picture of something bad happening on the left piece of matzah and a random picture on the right. Goal is to explain how the bad event turned out for the best using the random pic in the story. (1/2)

Fits the the theme of Yachatz that the bad part (smaller piece) came first, but it was all meant for the best in the end (bigger piece saved for later). (2/2)

Start the Seder with the game “21” but with the simanim. As a group, the entire order must be recited without two people speaking at once, without the same person going twice in a row and w/o any communication among the players.

Write the names of songs on slips of paper and fill a bag with them. Before certain/each parts of the Haggadah, randomly draw a slip as use that tune to read the next section. (Make sure to pick tunes that will likely match the words so that it doesn't ruin the Haggadah.)

The Four Sons - How well do you know your children? Play the newlywed game with your kids right before reading the Arba'a Banim: Pair up parent with child. Parent leaves room and child is asked questions about himself or herself. Parent is called in to guess the answers. (1/2)

Afterwards, discuss whether these facts are important for a parent to know about their child or not. Can lead to discussion about why a parent needs to know their children well, which is the theme of the Four Sons. Obviously, adjust based on age. (2/2)

Play a makkot-themed game of Would You Rather...? (Would you rather have frogs on your head or in your bed? Would you rather it be dark for you but light for everyone else or dark for everyone?)

For Arami Oved Avi: Have a debate between Avraham, Yaakov, Yosef, and Jewish slave about who had a bigger challenge in life (and therefore needed the most help from Hashem)

For Arami Oved Avi: Print out sheets of paper each representing a major event leading up to Yetziyat Mitzrayim (and beyond) and mix them up. Have kids try to put them in order. (1/2)

Other option is to have sheets representing each part of Arami Oved Avi and have attendees hold up the right sheet at the correct part of the Haggadah.

Good idea to create a type of currency to give out to kids who participate in the Seder. Set a goal for all the kids to reach together to earn a prize (prize should be based on the collective number so that there is no competition).

Also PREPARATION IS . Have your family members sign up for different parts of the Haggadah beforehand so that they are prepared to participate. Nothing worse than a power struggle at the Seder to get kids to participate. This will largely help avoid such conflicts.

Pesach, Matzah, and Marror is a perfect time to get into trivia questions. Ask age-appropriate questions for each of the mitzvot.

Dayeinu is the perfect time to model hakarat hatov for your kids. Write your own Dayeinu and sing it beforehand to set the tone. Good idea to print pictures for each dayeinu in the Haggadah to increase understanding and connection.