Its all a game, on both parts,
Take it from me, a player, I do what you described when I want to build desire in the other person and it totally worked on you. Don't believe me? Your thinking of him and why he's doing that, its gotten to you so much you had to come on to here to ask about it face it you're stuck thinking about him hardcore not that its a bad thing and not that he's a player I'm just telling you the psychology of it all.
Another thing I'll do is send my first few texts, that is if I EVER text which I hate because its so impersonal and cowardly in my opinion, but I digress. I'll send the first few texts in a quick response type thing then I'll gradually slow down the speed at which I replay throughout the day. This makes you girls wait for that next text in the same way as above, it keeps me on your mind as well as subconsciously makes me more valuable and seem like a harder catch because you wonder what's taking my attention away from you.
Any more questions about why guys do what we do when we game and I'd be glad to tell you just ask away, I help girls with this stuff all the time.