After 15 years of operating fantasy games, Sandbox.com has announced via a letter on its site (and e-mailed to users) that this season will be its last.

“The fantasy sports industry has changed significantly in the past few years and as Sandbox.com’s popularity declined, it became increasingly more difficult for us to offer you the kind of fantasy sports experience you deserve,” the letter states. “This is a decision that we did not make lightly, and we know that many of you will be disappointed. We’re disappointed too.”

Sandbox says it will allow all current seasons in football, college football, golf and NASCAR to complete and that it will officially close on January 7. The site is “recommending” that users move their leagues to CBSSports.com.

“They have been in the industry for over a decade and know how fantasy is done,” the letter says, regarding CBS. “To help with this transition, we are working with CBSSports.com to determine the best options for you to migrate your leagues over to their games.”

(This is a somewhat interesting partnership, considering that Sandbox has operated for the past few years under the ownership of NBC Sports, coming as part of the All Star Sports deal that also included Rotoworld.com.)

Sandbox.com opened with free games back in the mid-’90s — and was actually the first place this writer ever played — before switching to pay in the early 2000s. According to Compete.com, unique-visitor totals have hovered mostly near 20,000 a month in this final year.