Most noted for the funny look in his weird blue eyes, that toothy grin and those maniacal cackles we call laughter. Jackle is similar in physical appearance to NiGHTS, but twice their size and wearing a different color scheme (whites, red, oranges, yellows and light blues). His hat curls forward and inward over his head rather than backward and outward like NiGHTS/Reala's hats and he wears a large cape which makes him invulnerable. Finally, only his clothing (shoes, gloves, cape and hat), eyes and teeth are visible. However, whether this is due to his body being invisible or due to a complete lack of a physical body is debatable.
His boss room consists of oversized toys and instruments of torture in bright primary colors. The entire room is encased in red drapes reminiscent of a circus tent and is littered with toy blocks and blue and green dolls with crazed looks on their faces. Two notable items in his boss room are a gigantic purple and yellow star-print jack-in-the-box and an oversized red and yellow guillotine.
Jackle fights by throwing razor-sharp tarot cards that slow NiGHTS down on impact. The player needs to remove his cape to make him vulnerable, by evading his projectiles and dashing into him. Once he's lost his cape, he will no longer attack, and NiGHTS will be free to damage him by touch-dashing him. Immediately, he will make a beeline for the safety of his cape again, so try and stand between them when attacking to halt his progress.
To score a 2.0, the player must have at least 105 seconds remaining.
- Jackle's theme song is titled "The Mantle".
- The guillotine in Jackle's level will drop on rare occasions.
- Due to his role as a third dream boss and his similarities in appearance to NiGHTS and Reala, many fans believe that Jackle is probably the highest ranked second level Nightmaren or even the third first level in Wizeman's army.
- Compared to every other Nightmaren currently shown, Jackle's appearance is the most similar to that of Wizeman.
- Jackle appears in the Nightmare Zone DLC for Sonic Lost World, as the Nightmaren that Zor is riding on.
- Jackle's body being mostly invisible, sparing his eyes and smile, is very similar to the Cheshire Cat in Lewis Carroll's 'Alice in Wonderland'. The room he's fought in also has similarities to some of the rooms seen in the Walt Disney animated adaption of the story. This seems to not be a coincidence, as both stories take place in a dream.
- Soft Museum and Jackle represent growth, with the museum representing maturity, the garden outside representing growth, and fighting Jackle in the playroom-styled arena represent Claris Sinclair trying to move on from childhood to the next part of life. She's trying to mature and not run away from her problems like she did during her first audition for Twin Dreams.
- Although he does not appear in the NiGHTS Pinball stage from Sonic Adventure DX, when inspecting the textures for that stage, an unused Jackle card can be seen.