This wasn't an official Atari title. The programmer, Mark Hahn, did it in his spare time, and offered it to Atari, but they declined it. From Hahn:
From the programmer: "The history of Elk Attack is not very interesting. In the spring of 1987, finding myself unemployed, I wrote a VCS game based very loosely on Yo-Yo. Those things that were easy to do I did; those that were hard, I changed or dropped. I named my cart Elk Attack as a joke and sent the cart to Atari and Epyx for them to evaluate. Neither were interested, so I stuffed my test EPROMS in a drawer and forgot them until I ran across the STELLA emulator. Brad Mott had a wonderful emulator but no binaries to distribute with it. I gave him permission to include Elk Attack with distributions of STELLA."