They are represented by the symbol , which is the color inverse of the usual positive Level symbol. On a card, negative Level Stars align to the left, whereas positive Level Stars align to the right.
In the Tag Force series of video games, Dark Synchro Monsters use the same card frame they use in the anime, but the cards themselves have positive Levels. They are affected by the effects of cards such as "Burden of the Mighty" and "Level Limit - Area B" the same way any other monster their Level would, and they can be used as Synchro Material. From Tag Force 6 onwards, they can also be used as Xyz Material.
When Dark Synchro Monsters were released in the OCG/TCG, they were all changed to regular Synchro Monsters with their Levels changed to the appropriate positive value.
- "Yu-Gi-Oh! Tag Force 6 Dark Synchro Xyz vs Vizor | YouTube". October 13, 2011. Retrieved May 30, 2017.