Christmas NiGHTS is an extended demo of the original NiGHTS: Into Dreams. Featuring identical gameplay, it gives players the opportunity to play as either Claris Sinclair or Elliot Edwards (as well as the game's namesake, NiGHTS) in the level "Spring Valley" reskinned to match whatever season it is in real life. (Determined by the Sega Saturn's internal clock.) Like the original NiGHTS into Dreams, the ultimate goal of the level is to fly around and reclaim the four "Ideya" spheres that have been stolen from you. After collecting an Ideya from an ''Ideya Capture'' the player must return to the Ideya Palace at the start of the level to be graded on their performance and to start their quest for the next one. Collect all four, and players face off against a boss: in the case of the demo, a giant winged lizard called Gilwing.
Unique to Christmas NiGHTS is a bevvy of holiday-themed goodies - the biggest of which being the title's namesake; if the Sega Saturn's internal clock is anytime within the month of December, the entire demo transforms to feature an all-new Christmas-based storyline and visual style, in which Elliot, Claris, and NiGHTS are tasked with retrieving the missing Christmas Star for the city's giant Christmas Tree display. Christmas NiGHTS's version of Spring Valley is completely revamped with holiday graphics and music, and NiGHTS itself is decked out in a Christmas costume. Playing Christmas NiGHTS at any other time of the year will simply result in the game referring to itself as "NiGHTS: Limited Edition".
Completing "Spring Valley" as either Claris or Elliot will reveal an icon-matching Memory minigame. Match two icons and players will unlock that specific extra. Which extra the player unlocks corresponds to which icons they matched. The extras in Christmas NiGHTS are surprisingly extensive for a demo, including things such as concept art image galleries, archival video of NiGHTS into Dreams trailers from the Tokyo Game Show, enhanced music players, tools to analyze the player's save data and progression from the full retail version of NiGHTS into Dreams, and even a bonus mode where players get to control Sonic the Hedgehog running around Spring Valley with 3D gameplay, ending with a custom boss fight against Dr. Ivo "Eggman" Robotnik. (Which turns out to be a reskinned version of one of the bosses from NiGHTS into Dreams, although playing as Sonic instead of Nights provides a gameplay twist.)
If the player completes Spring Valley as both Claris and Elliot in a single sitting, the ending to the game will play out, complete with the game wishing the player "Merry Christmas".
- Spring Valley (This is in fact an all new stage, although the same environment.)
- Frozen Bell, for Link Attack Mode. (But only MARE 1 is used. The full stage remains exclusive to NiGHTS into Dreams.)
- Although not a new stage, Sonic can be unlocked and played as in Spring Valley. (His gameplay is similar to playing as Claris and Elliot, but Sonic is slightly more powerful than they are.) This mode is called ''Sonic into Dreams''.
The unlockable content in Christmas NiGHTS includes:
- This makes up the bulk of the unlockables in Christmas NiGHTS. There are 15 image galleries total.
- The main theme song of NiGHTS into Dreams, "Dreams Dreams", plays with viewable lyrics and various audio altering options.
Link Attack Mode
- Try to keep your "link combo" going as long as possible in the first section of Frozen Bell, from the full version of NiGHTS into Dreams.
Time Attack Mode
- Collect all the items in the first section of Spring Valley as quickly as possible.
- Listen to all the 20 different variations of each song from all the levels in NiGHTS into Dreams.
- Check the moods of all the hundreds of little Artificial Intelligence creatures that populate the levels in your save file for the full version of NiGHTS into Dreams.
- View both the Tokyo Game Show 1996 and Summer Special 1996 trailers for NiGHTS into Dreams.
''SONIC into Dreams''
- Run around Spring Valley as Sonic the Hedgehog as you race against the clock to complete the level on foot.
- Unlocked by playing on April Fools Day, this option allows you to play as Reala, a boss character commonly known as NiGHTS's evil twin from NiGHTS into Dreams.
- After completing Christmas NiGHTS, you are given the option to play it at any time of the year.
The music for both NiGHTS into Dreams... and Christmas NiGHTS was composed by Naofumi Hataya, Tomoko Sasaki, and Fumie Kumatani. The game contains one vocal track which is "Dreams Dreams", by Akira Sasaki with vocals by Curtis. King Jr., and Dana Culitri
- The concept of changing seasons and holiday-themed costumes for Christmas was something SonicTeam wanted to implement in the main NiGHTS into Dreams game, but did not have time to.