[1][2] Both coasters opened in 1976 as Turn of the Century, when both Great America parks were owned by Marriott Corporation.

The airtime hills after the first drop were removed and replaced with two consecutive vertical loops and a lighted tunnel.

With the addition of the loops, the Demon coasters became the second in the world to feature four inversions, after Carolina Cyclone at Carowinds which opened two months earlier.

[8] Fog machines were placed in the tunnels, blood red colored water fell out of the rock formation by the corkscrews, and a unique logo was unveiled.

[5] A large version of this logo was placed on the Demon's sign with a pool of red dyed water in front of it.

[7] These changes allowed the parks to market Demon as a new attraction for the 1980 season without having to construct a new roller coaster.

[9][10] In 2005, for Six Flags Great America's Fright Fest event, almost all of Demon's original theming returned.

Decals similar to the original logos were added to the noses of the trains, fog returned in the tunnels, the Demon song played in the queue again, and red lights and tiki torches were placed all around the ride.

Built from an oil barrel with red lights and fog, it was placed in the flower bed in front of the ride's sign.

[11] On the park's 2006 opening day, the Demon song continued playing in the queue, the decals were still on the front of the trains,[12] and the flames were still painted on the station.

[5] In 2009, Demon's black train was given airbrushed flames on the sides of the front car with no red stripe.

[5] Riders had the option to wear Samsung Gear VR headsets, powered by Oculus to create a 360-degree, 3D experience while riding.

The illusion was themed to a fighter jet, where riders flew through a futuristic city as co-pilots battling demonic creatures.

[32] During the queue, a 25 minute long soundtrack is played, including dialogue, sound effects, and the ride's theme song.

[2] After boarding the ride, riders start by traveling through a small tunnel with lights which turns slightly to the left.

[2] Next, riders fly through a tunnel containing red lights at 45 miles per hour (72 km/h), before climbing a small hill, where their speed significantly decreases.

At the top of the hill is the midcourse brake run and another pre-drop followed by a turn, this time with a slightly greater angle than 180°.

[36] In August of Turn of the Century's opening year, a wheel guide assembly fell off of a train on the version in Santa Clara.

[34][37] In 1993, two trains collided at low speeds in the station of the Gurnee ride due to a switch malfunction, causing injuries to eight people.

After the incident, the ride remained closed for a short period for repairs, following an investigation from the park staff and the fire department.

[40] Twenty-three riders were left stranded upside down after the black train came to an unexpected halt in the middle of one of the vertical loops.

A mechanical safety system built into the wheel assembly engaged, preventing the train from derailing.