You can do.
(zlib is a software licence)
CC-BY-SA 3.0 means:
-Attribute: Currently there is no guideline for properly attribute teeworlds licence afaik, so you should at least give credits like 'based on Teeworlds' (+link) (just an example). Think yourself what a proper attribute would be to make clear, who created that stuff, you used.
-Share Alike: You need to publish your work under the same licence like teeworlds, which means 'CC-BY-SA 3.0'
or are commonly used for shortening
Note: If you have trouble with the english text, at the bottom you can choose your language and for further details read the legal code :http://creativecommons.org/licenses/by-sa/3.0/legalcode