The game was a Christmas gift from the Sonic Team. In Japan it was given to subscribers of the Famitsu magazine for the Christmas of '96. In the US, it was packaged with the Next Generation and Game Players magazines, also around the holiday of '96. In Europe it was first only bundled with certain Saturn packages or given as a promotional item when you bought two Saturn games, however a year later in '97 it was available with the December issue of Sega Saturn Magazine.
Here are the dates where the content of the game changes.
- March to October: Standard Christmas NiGHTS into Dreams... content.
- November, January to February: Winter theme, with snow and accordingly fitted outfits for Claris and Elliot.
- December 1-25: 'Tis indeed the season in Spring Valley on these dates, with a joyful Christmas theme! Lots, and lots of changes. This is also the only time you'll be able to see the intro and end movies. However, if you complete the game under these dates the Christmas setting will be playable at any time -- through the Presents menu.
- January 1: Same content as the Winter setting, however with a new years greeting at the title screen.
- April 1: Go to the Ideya Palace and you will be able to play as Reala. Complete the game as him, and he'll be available to play at any time via the Presents menu.
Should you not have the patience to wait around you can change the Saturn's internal clock which is used to trigger the content.