Your actions make it pretty clear to her that you are okay with friendship, otherwise you wouldn't keep chatting away with her. Perhaps that's all she wants is to be friends; no ulterior motive at all.
I'm not sure what to tell you. Is it true that you can't be friends only with her? If that's all this is, will it be enough for you? I suspect not, but only you know that.
1) I wouldn't give any ultimatums. That's pretty controlling. 2) Decide if friendship is enough 3) If you can't just be friends, then I suggest you start being less friendly. You can still greet her nicely, but don't get into big conversations with her. If she calls about the game, either don't bother answering, or make it very short and say, "I gotta go" and get off the phone.
Me
In the end, it's not the years in your life that count. It's the life in your years. Abraham Lincoln
It is hard to fail, but it is worse never to have tried to succeed. Theodore Roosevelt
