Does Samadhi realm of desire require single-pointed focus? I read there are 3 realms of samadhi: realm of desire, realm of form and realm of no form.

If I read correctly, Samadhi is one-pointed focus. But if I achieve samadhi by, let's say, the desire to win a sports game: I'm locked in, well doesn't my mind have to be focused on many aspects? There isn't a single-pointed focus, of having only one object like a kasina, in mind. Same for form.  Can one still achieve one-pointed focus with multiple things in mind, if he is only focused on them and nothing else? Can I still reach happiness and the other jhana factors?
There are no 3 realms of Samadhi(Jhana). The jhanas have nothing to do with sensual desire. First four jhanas lead to birth in fine material realms. The last four lead to immaterial realms. One-pointeness by definition is pointed at one object. At that moment all sensual desires are subdued. 

But it is possible to get in and out of the Jhanic  states quickly if you master them. ex: It is said that the Buddha enters the Jhanas between each word he speaks while maintaining a normal speaking speed.