In what situation (if any) you would say "better play positive"? Please, don't add any punctuation between words.
You could say:
... or is that cheating?
It's possible someone would say
but to me this sounds a little strange: formal English would have "positively"; "positive" seems a strange choice of words for saying this colloquially, but it wouldn't surprise me too much if someone used this in analogy to the phrase "think positive" which is well-known, or having heard the phrase "positive play". (It's also possible it sounds more natural in the US or in a particular dialect, but someone else will have to comment on that :-)
Here the words, 'better play positive' mean that you better start thinking positively or negativity will not help you solve your problems.
@brilliant- For what situation do you want those words?