Thankfully, you are very, very wrong!
The game has been in constant development since 0.9, and if you ever need to see what changes have been made lately, simply navigate to the github page, at https://github.com/CleverRaven/Cataclysm-DDA
The next new version of C:DDA will be 0.A, and it won’t be released for a good long while as the contributors are working on the NPC rewrite, creature changes, and other huge and monstrous tasks.
If you want your tileset main game, I think once it’s complete all you have to do is release it to the contributors under a license that allows them to use it without breaking any laws. Cataclysm, for example is licensed under the Creative Commons Attribution-ShareAlike 3.0 Unported License, the terms of which are visible here http://creativecommons.org/licenses/by-sa/3.0/us/
Talk to Glyphgryph or others in chat or forum if you want to get the tileset merged. I am not a contributor, and probably can’t help you there.