You can download MyKaryotes and the MyKaryotes Standard Cell Editor here. The MyKaryotes.zip archive contains the game executable (and the source, if you want to compile it yourself), some readme information, and a couple sample specimens and terrain to help get you started. You can also download the latest Stable versions from MyKaryotes' page at YoYo Games and the MyKaryotes Standard Cell Editor's page there. If you try MyKaryotes or the Editor out, I'd appreciate it if you went back to its page and rate/comment there.
The downloads under the Stable section indicate the latest stable version(s) of MyKaryotes and the Standard Cell Editor. This is what most users will want, as they represent official releases of MyKaryotes and can be considered relatively stable.
The Development Builds section has been removed for now since the final release of the Game Maker version of MyKaryotes has been made. The builds in the Stable section are now the absolute latest public releases. Thanks for your testing up until this point, and please continue to test the Stable builds! The Stable builds will be updated from time to time as any remaining bugs are found and fixed.
Official MyKaryotes-related goodies can also be found on this page, like wallpapers and such.
You can also check out other downloads in Related Stuff, such as related projects, extra terrain/specimen packs by others, etc.
MyKaryotes wallpaper by Christopher Kyle Horton is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 3.0 Unported License.