The game is no longer listed on LEGO.com, but can be accessed here.
The player is given 60 seconds in the game.
They must guess which two Mixels are used in the Mix shown on each level, based on the ones shown. If the player gets it correct, they will obtain a Cubit. Getting four in a row correct would give the player a time boost power-up. If unsuccessful, the image of the Mix will be blocked by the Nixels thumbs-down symbol, and the player will continue to the next level without the Cubit awarded and will lose all stars.
Throughout the game, Nixels appear on the Mix image and block the player's view, making it a challenge for the player. This can be easily removed using the bomb power-up that sometimes appears on the screen. Another power-up consists of a time boost of either five or ten seconds, the ten second one sometimes automatically appearing after a few correct answers.
Once finished, the player is able to view the gallery of Mixes that the player has guessed correctly.
- This game is the sequel to Mixels Mania. As such, no series later than series 3 appear in Mixels Mania, while only Series 4, 5 and 6 Mixels appear in Who's In The Mix.
- At the end of the game when you win, you can hear music from the beginning of Mixed Up Special (specifically, Epic Comedy Adventure). After it finished, the credits music from the same episode will play on loop.
- When the game was first released, it automatically began when the player clicked the Games tab. A few days later, an extra page was added to click on.
- Various foreign Mixels websites lacked this game.
- Instead of having separate modes for each series, like Mixels Mania, this game combines all of the Mixes of all three series, lengthening the game options with each update.
- The game sometimes freeze after it ends, causing the results screen to never show up, with the music merely looping on a blank background.
- When clicking two Mixels after clicking a bomb, the game may freeze.
- In the Series 6 update, certain Mixels have two combinations, for example, there's two combinations between Dribbal and Forx. The game registers one combination as a combination of them, but the other combination is registered as a combination of Gurggle and Forx instead.
- The mixes between the three Munchos are swapped around.
- Main article: Who's In The Mix/Gallery