I think I should change the phrasing I used. Let's say that every msg has value, and every sentence in a msg has value. The goal is to use certain values that convey and instill the presence or lack of feeling.
Lets start with a very neutral sentence:
"Let's hang out this weekend."
Things that could give this sentence a positive value would be an exclamation point, the use of the word "we" (implies that the two of you are a unit) instead of "Let's," and something that conveys this as an absolute like the word "should."
Positive revision:
"We should hang out this weekend!"
Positive values can also be achieved with the use of emoticons. Emoticons such as ; ) are also important to signify that you're joking. Personally, I try not to use anything other than ; )

:'(
Make sure to balance how you weight sentences in a positive message. You shouldn't use an exclamation, an emoticon, a referral to her, and an absolute statement all in the same sentence, or else you will come across as overbearing.
Instead, give the first sentence positive value by referring to her. Use the emoticon for the sentence that is most joking. Throw an exclamation point onto your most neutral statement (or you could turn a question (negative) into a positve by adding a exclamation point ?!)
If you wanted, we could also give this sentence a negative value.
negative revision:
"Want to hang out this weekend?"
Even though the chick has always had a choice in the matter, now we've admitted that the choice is there. This adds negative value. Making this a question also adds negative value.
Negative valued sentences aren't always a bad thing though! For example, after a string of positive messages a negative message stands out- also true when a negative sentence is within a mostly positive message. This concept should only be used with extremely negative values, though.
Extremely negative revision:
"If I'm not too busy, maybe I can make time to hang this weekend."
This refers to "I" multiple times, which is always negative in texting. It also lacks sureness by using the word "maybe." These things make this a negative statement, but what makes it a extremely negative statement is the tone of the message. It implies that the choice is up to you, that you might have better things to do than hang with the girl, and that you really don't care whether you do or not. The implementation of these final things ultimately have less to do w/ text game and more to do with inner game.
Some things to remember:
There is almost never anything wrong with positive messages.
Negative messages usually make you appear weak.
Neutral messages (neither negative nor positive) will make you seem boring, unless used rarely and in the presence of un-neutral messages (in this case they convey the sense that you are getting bored or that the girl has done something wrong).
Extremely negative messages are risky because they are overdramatic and should only be used once you understand both texting and normal conversation skills.
Summary:
The entire point of giving your sentences and messages value is to charge them with subtext. Every single sentence shouldn't just be saying something, but it should be piquing some subconscious interest and be conveying something more than what is said.
And to answer your question, no. The only sources of text game I've found are text openers. As soon as I have time, I'll go into even more detail and break down everything there is to my text game as a separate post.